As filed with the Securities and Exchange Commission on
                                February 8, 2001

                                File No. 70-9633

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                -------------------------------------------------

                        POST-EFFECTIVE AMENDMENT NO. 6 TO
                             APPLICATION-DECLARATION
                                   ON FORM U-1
                                    UNDER THE
                   PUBLIC UTILITY HOLDING COMPANY ACT OF 1935
                -------------------------------------------------
                               UNITIL CORPORATION
                            CONCORD ELECTRIC COMPANY
                        EXETER & HAMPTON ELECTRIC COMPANY
                    FITCHBURG GAS AND ELECTRIC LIGHT COMPANY
                               UNITIL POWER CORP.
                               UNITIL REALTY CORP.
                              UNITL RESOURCES INC.
                              UNITIL SERVICE CORP.
                               6 Liberty Lane West
                        Hampton, New Hampshire 03842-1720
                ------------------------------------------------
                  (Name of companies filing this statement and
                     address of principal executive offices)

                               UNITIL CORPORATION
                               6 Liberty Lane West
                        Hampton, New Hampshire 03842-1720
                -------------------------------------------------
                 (Name of top registered holding company parent)

                                 Mark H. Collin
                                    Treasurer

                               UNITIL CORPORATION
                               6 Liberty Lane West
                        Hampton, New Hampshire 03842-1720
                -------------------------------------------------
                     (Name and address of agent for service)









                  The Commission is requested to mail copies of
                   all orders, notices and communications to:

                          Joanne C. Rutkowski LeBoeuf,
                          Lamb, Greene & MacRae, L.L.P.

                           1875 Connecticut Ave., N.W.
                              Washington, DC 20009










     This post-effective amendment amends and restates Post-Effective Amendments
No. 4 and 5 to File No. 70-9633.

     Unitil Corporation, a New Hampshire corporation ("Unitil") and a registered
holding company under the Public Utility Holding Company Act of 1935, as amended
(the "Act"), and its wholly owned subsidiary companies, Concord Electric Company
("Concord"),  Exeter & Hampton  Electric Company  ("Exeter"),  Fitchburg Gas and
Electric  Light  Company  ("Fitchburg"),  Unitil Power Corp.  ("Unitil  Power"),
Unitil  Realty  Corp.  ("Unitil  Realty"),   Unitil  Resources,   Inc.  ("Unitil
Resources")  and Unitil  Service  Corp.  ("Unitil  Service"  and,  together with
Concord,  Exeter,  Fitchburg,  Unitil Power, Unitil Realty and Unitil Resources,
the  "Subsidiaries"  or "Money Pool  Participants")  hereby request increases in
certain authorized borrowing amounts.1 As explained more fully below, Applicants
require relief on an expedited basis and so ask the Commission to issue an order
granting the requested authority no later than January 31, 2001.

     On June 9, 2000,  Unitil and the  Subsidiaries,  received  authority  under
Sections  6(b),  7,  9(a),  10 and  12(b) of the Act and the Rules 43, 45 and 52
thereunder with respect to (i) short- term borrowing by Unitil,  (ii) short-term
borrowings  by Fitchburg  and (iii) the  continued  use of the system money pool
("Money Pool") by Unitil and the Money Pool  Participants,  pursuant to the Cash
Pooling and Loan Agreement (the "Pooling  Agreement") among Unitil and the Money
Pool  Participants  dated as of  February 1, 1985,  as amended,  Holding Co. Act
Release  No.  27182 (the  "Order").  On  December  15,  2000,  in  response to a
post-effective amendment, the Commission authorized Unitil to increase its short
term borrowing to $35 million. Holding Co. Act Release No. 27307 (Dec. 15, 2000)
("Post-Effective Amendment No. 3").

     The Applicants hereby file this post effective  amendment  ("Amendment") to
their  application-declaration  on Form  U-1  relating  to the  above-referenced
transactions (the "Original  Application-Declaration") under the Act in order to
increase certain authorized borrowing amounts authorized in the Order.

ITEM 1.  DESCRIPTION OF PROPOSED TRANSACTIONS

     The Applicants  hereby submit this Amendment for authorization and approval
under  Sections  6(a), 7, 9(a), 10 and 12(b) of the Act and the Rules 43, 45 and
52  thereunder  to increase  Unitil's  authorized  short-term  borrowing  to $45
million from $35 million and Fitchburg's  authorized short-term borrowing to $30
million from $20 million.  The prices that Unitil's  subsidiaries,  Unitil Power
and Fitchburg, pay for wholesale electric and natural gas energy commodities has
become  unpredictably  volatile and has sharply  risen putting a heavy strain on
Unitil's working capital and  significantly  increased its short-term  borrowing
requirements.  Despite  the  recent  granting  of rate  relief  from  the  state
regulatory authorities,  rising wholesale energy commodity costs are expected to
continue  at this time to  outstrip  the effect of such  relief  reflecting  the
inherent  lag  in  the  regulatory  cost  recovery   process.   The  Applicant's
subsidiaries  are  absorbing an  increasing  portion of these costs by deferring
such energy costs for recovery in a

- --------
     1 For purposes of this Application-Declaration, Unitil and the Subsidiaries
are collectively referred to as the "Applicants".



                                        1






later period.  Despite recent  authorized  increases in the borrowing  authority
granted to Unitil and Fitchburg by this Commission and the above-mentioned  rate
relief,  the  Applicants  are  currently  experiencing  an acute  need to borrow
additional  funds to  principally  satisfy  the cost of their  wholesale  energy
obligations.  Applicants  expect  that  this  is  a  temporary  phenomenon,  but
nevertheless  one  which  requires  additional  borrowing  authority  to  enable
Applicants  to  pay  for  wholesale  natural  gas  and  electricity   purchases.
Accordingly,  Applicants  ask  the  Commission  to  Expeditiously  approve  this
Amendment.

     Unitil's Board of Directors  authorized this short-term  borrowing limit of
$45 million on January 16, 2001, and Fitchburg's  Board of Directors  authorized
the new limit of $30 million on the same date. See Exhibits B-2 and B-3.

     Any  borrowings  undertaken  pursuant  to this  authorization  will  remain
subject to the parameters set forth in the Order,  as  supplemented,  except for
the  new  aggregate  limits  of $45  million  for  Unitil  and $30  million  for
Fitchburg.  While some of these  parameters  are  discussed  or repeated in this
Amendment, the decision not to repeat or describe a specific aspect of the Order
or Original Application-Declaration does not affect its continuing validity.

     After the  Commission  authorized  the  borrowing  authority  requested  in
Amendment  No. 3, Unitil  began to utilize this new  authority  and had incurred
approximately $33 million in short term debt as of December 31, 2000.

     As  discussed  in the  Original  Application-Declaration,  Unitil  requests
authority  to secure  both  formal and  informal  credit  lines with a number of
lending  institutions.  Formal credit lines under the proposed facilities may be
subject to compensating  balances and/or fee requirements.  Compensating balance
requirements  will not exceed 5% of the committed  credit line amount,  and fees
will not exceed 50 basis points times the total line of credit per annum. Unitil
may change its credit line arrangements and obtain additional formal or informal
credit lines over time.

     Applicants  anticipates  that most of Fitchburg's  borrowings  will be made
through the Money Pool. However, the Fitchburg board resolutions do not prohibit
Fitchburg  from  short-  term  borrowing  outside  of  the  Pooling   Agreement.
Accordingly,  Fitchburg seeks Commission authorization for short-term borrowings
up to $30  million  through the Money Pool and through  direct  borrowings  from
commercial banks on terms similar to those on which Unitil borrows.

     The proposed transactions are not subject to Rules 53 and 54 under the Act.
Neither Unitil nor any Subsidiary  thereof presently has, or as a consequence of
the  proposed  transactions  will have,  an  interest  in any  exempt  wholesale
generator  ("EWG") or  foreign  utility  company  ("FUCO"),  as those  terms are
defined in Sections  32 and 33 of the Act,  respectively.  None of the  proceeds
from the proposed transactions will be used to acquire any securities of, or any
interest  in,  an  EWG  or  FUCO.  Moreover,  neither  Unitil  nor  any  of  the
Subsidiaries is, or as a consequence of the proposed transactions will become, a
party  to,  and such  entities  do not and will not  have any  rights  under,  a
service, sales or construction contract with any affiliated EWGs or FUCOs except
in accordance with the rules and regulations  promulgated by the Commission with
respect  thereto.  Consequently,  all applicable  requirements of Rule 53(a)-(c)
under the Act are satisfied as required by Rule 54 under the Act.


                                        2






ITEM 2.  FEES, COMMISSIONS AND EXPENSES

     The fees, commissions and expenses of the Applicants expected to be paid or
incurred,  directly or indirectly, in connection with the transactions described
above are estimated as follows:

Legal fees                       ...................................... $5,000
Miscellaneous                    ...................................... $3,000
                          Total  ...................................... $8,000

ITEM 3.  APPLICABLE STATUTORY PROVISIONS

     Sections  6(a),  7, 9(a),  10 and 12(b) of the Act, and Rules 43, 45 and 52
thereunder, are directly applicable to this Application-Declaration as follows:

     (1) External Borrowings by Unitil and Fitchburg (Sections 6 and 7).

     Sections  6  and 7  apply  to  Unitil  and  Fitchburg's  request  to  incur
     short-term debt.

     (2)  Regulation of the Money Pool (Sections 6, 7, 9, 10 and 12(b) and Rules
     43, 45 and 52).

     Sections 6, 7, 9, and 10 and Rule 52 govern  operation  of  Unitil's  Money
     Pool.  Section 12(b) and Rules 43 and 45 also apply to  transactions  among
     registered holding companies,  their subsidiaries and companies in the same
     holding  company system and prohibit the  transactions  contemplated by the
     Money Pool without prior Commission authorization.

     As  previously  described in  Pre-Effective  Amendment No. 2 to Form U-1 in
File 70-9633,  filed with the  Commission on May 23, 2000, the Unitil Money Pool
may function  under Rule 52 without  commission  approval.  Concord,  Exeter and
Unitil  Power  have  received  orders  from  the New  Hampshire  Public  Utility
Commission  authorizing their  participation in the Money Pool. See Exhibits D-1
and  D-2.  Likewise,   Fitchburg  may  participate  pursuant  to  order  of  the
Massachusetts  Department  of  Telecommunications  and Energy.  See Exhibit D-3.
Unitil Realty, Unitil Resources and Unitil Services are non-utility subsidiaries
of Unitil  whose  short-term  borrowings  will be used solely for the purpose of
financing their respective  businesses at interest rates and with maturity dates
that would parallel such lender's  effective  short-term  cost of capital on any
given date.  Accordingly,  such  transactions are exempt from the prior approval
requirements of Section 6 of the Act under Rule 52(b). Unitil may participate in
the Money Pool pursuant to Rule 52(d).

ITEM 4.  REGULATORY APPROVALS

     The New  Hampshire  Public  Utilities  Commission  has  authority  over the
participation of Unitil, Concord, Exeter and Unitil Power in the Money Pool, and
has issued an orders  approving  participation.  See  Exhibits  D-1 and D-2. The
Massachusetts Department of Telecommunications



                                        3






and Energy has authority over  Fitchburg's  participation in the Money Pool, and
has issued an order approving participation. See Exhibit D-3.

ITEM 5.  PROCEDURE

     It is requested that the Commission issue and publish no later than January
12, 2001 such notice  specifying  January 27, 2001 as the date by which comments
may be  entered  and the  date on which an order  granting  and  permitting  the
Application-Declaration to become effective may be entered by the Commission and
that the Commission enter not later than January 31, 2001, an appropriate  order
granting and permitting this Application-Declaration to become effective.

     The Applicants  respectfully  request that appropriate and timely action be
taken by the  Commission in this matter.  No  recommended  decision by a hearing
officer or other responsible  officer of the Commission is necessary or required
in this matter.  The Division of  Investment  Management of the  Commission  may
assist in the  preparation of the  Commission's  decision in this matter.  There
should be no thirty-day  waiting  period between the issuance and effective date
of any order issued by the  Commission  in this matter,  and it is  respectfully
requested  that any such  order be made  effective  immediately  upon the  entry
thereof.

ITEM 6.  EXHIBITS AND FINANCIAL STATEMENTS

     a)   Exhibits

            Exhibit No.                  Description of Exhibit
            -----------                  ----------------------

                B-1      Cash Pooling and Loan Agreement, as amended (previously
                         filed with Post-Effective Amendment No. 1).

                B-2      Resolutions of Fitchburg Board of Directors authorizing
                         short-term borrowing limit of $30 million.

                B-3      Resolutions  of Unitil Board of  Directors  authorizing
                         short-term borrowing limit of $45 million.

                D-1      New Hampshire  Public  Utilities  Commission  Order No.
                         18,416  (Filed  on Form SE and  previously  filed  with
                         Pre-Effective  Amendment  No. 2 to Form  U-1,  File 70-
                         9633).




                                        4







                D-2      New Hampshire  Public  Utilities  Commission  Order No.
                         17,373  (Filed  on Form SE and  previously  filed  with
                         Pre-Effective  Amendment  No. 2 to Form  U-1,  File 70-
                         9633).

                D-3      Massachusetts   Department  of  Telecommunications  and
                         Energy  (formerly the  Massachusetts  Public  Utilities
                         Commission)  Order No. MDPU 89-66 (Filed on Form SE and
                         previously filed with Pre-Effective  Amendment No. 2 to
                         Form U-1, File 70- 9633).

                F-1      Opinion of Counsel.

                F-2      "Past  Tense"  Opinion  of  Counsel  (to  be  filed  by
                         amendment).

                H-1      Proposed Form of Notice (previously filed).

          b)   Financial Statements

                No.                  Description of Financial Statement
                ---                  ----------------------------------

                FS-1     Actual and Pro Forma  Balance  Sheet and  Statement  of
                         Earnings for the period ending September 30, 2000 for:

                         (a) Fitchburg;
                         (b) Unitil Corporation and Subsidiary Companies; and
                         (c) Unitil Company only (previously filed).

                FS-2     Unitil    Corporation    and    Subsidiary    Companies
                         Consolidated  Actual  Balance  Sheets and  Statement of
                         Earnings, September 30, 2000 (filed with the Commission
                         with Unitil's  10-Q for the period ended  September 30,
                         2000 and incorporated by reference herein).

ITEM 7.  INFORMATION AS TO ENVIRONMENTAL EFFECTS

     None of the matters  that are the  subject of this  Application-Declaration
involve a "major federal action" nor do they  "significantly  affect the quality
of the human  environment"  as those terms are used in Section  102(2)(C) of the
National  Environmental  Policy Act. None of the proposed  transactions that are
the subject of this Application-Declaration will result in changes in


                                        5





the operation of the Applicants that will have an impact on the environment. The
Applicants  are not  aware  of any  federal  agency  which  has  prepared  or is
preparing an  environmental  impact  statement with respect to the  transactions
proposed herein.

                                    SIGNATURE

     Pursuant to the  requirements  of the Public Utility Holding Company Act of
1935, the Applicants have duly caused this  Application-Declaration to be signed
on their behalf by the undersigned thereunto duly authorized.

Dated:  February 8, 2001
                                                  UNITIL CORPORATION


                                                  By: /s/ Mark H. Collin
                                                     -------------------
                                                  Name:    Mark H. Collin
                                                  Title:   Treasurer



                                        6


                                                                     EXHIBIT B-1

                               Unitil Corporation

                                   CERTIFICATE

                      ------------------------------------

     On motion  duly  made and  seconded,  the  following  vote was  unanimously
adopted:

VOTED:    That,  effective  January  16,  2001,  and  until  further  action  by
          Directors in this respect,  the total amount of  short-term  unsecured
          obligations  of this Company  issued and  outstanding  at any one time
          shall not exceed the sum of Forty-five Million Dollars  ($45,000,000);
          and that the Chairman,  President, and Vice President and Treasurer or
          any  Assistant  Treasurer of this Company be and they are, and each of
          them singly is,  hereby  authorized  to borrow  funds upon  short-term
          unsecured  obligations  of this Company not exceeding in the aggregate
          the  amount  above  set  forth,  bearing  interest  at such  rates and
          maturing  at such  time  as may to them  seem  wise,  such  short-term
          unsecured  obligations  to be signed on behalf of this  Company by the
          Treasurer  or  any  Assistant   Treasurer  and  countersigned  by  the
          Chairman, President, any Vice President, or any two Directors.

     I,  Mark  H.  Collin,   hereby  certify  that  I  am  Secretary  of  Unitil
Corporation;  that  the  foregoing  is a true  copy  from the  records  of votes
unanimously  adopted at a meeting of the  Directors  of said Company duly called
and held  January  16,  2001,  at which  meeting a quorum was present and acting
throughout;  and that the said  votes have not since  been  altered,  amended or
rescinded.

     WITNESS my hand and the corporate seal of Unitil  Corporation this 16th day
of January, 2001.

                                                          [SEAL]

                                                          /s/ Mark H. Collin

                                                          Secretary

                                                                     EXHIBIT B-2

                    Fitchburg Gas and Electric Light Company

                                   CERTIFICATE

                      ------------------------------------

     On motion  duly  made and  seconded,  the  following  vote was  unanimously
adopted:

VOTED:    That,  effective  January 16,  2001,  the total  amount of  short-term
          unsecured obligations of the Company issued and outstanding at any one
          time shall not exceed the sum of Thirty Million Dollars ($30,000,000);
          and that the Treasurer or any  Assistant  Treasurer of this Company be
          authorized  in the name and on behalf of this  Company to borrow funds
          upon short-term  unsecured  obligations of this Company  consisting of
          promissory notes and/or through short-term  borrowings  provided under
          the Unitil  Cash  Pooling and Loan  Agreement,  not  exceeding  in the
          aggregate  Thirty Million Dollars  ($30,000,000),  bearing interest at
          such rates and  maturing  at such times as may to them seem wise;  and
          any short-term unsecured  obligations shall be signed on behalf of the
          Company by the Treasurer or any Assistant  Treasurer and countersigned
          by the President, any Vice President or any two Directors.

     I, Sandra L. Whitney,  hereby  certify that I am Clerk of Fitchburg Gas and
Electric  Light  Company;  that the foregoing is a true copy from the records of
votes  unanimously  adopted at a meeting of the  Directors  of said Company duly
called and held  January  16,  2001,  at which  meeting a quorum was present and
acting throughout;  and that the said votes have not since been altered, amended
or rescinded.

     WITNESS my hand and the corporate  seal of Fitchburg Gas and Electric Light
Company this 16th day of January, 2001.

                                                        [SEAL]

                                                        /s/ Sandra L. Whitney

                                                        Clerk

                                                                     Exhibit F-1

                     LeBoeuf, Lamb, Greene & MacRae, L.L.P.
            A Limited Partnership Including Professional Corporations
                               260 Franklin Street
                              Boston, MA 02110-3713

                                                February 7, 2001


Securities and Exchange Commission
450 Fifth Street, N.W.

Washington, DC 20549

Sir or Madam:

     This opinion is furnished to the  Securities and Exchange  Commission  (the
"Commission")  in  connection  with   Post-Effective   Amendment  No.  5  to  an
application-declaration  on Form U-1 (File 70-9633)  ("Post-Effective  Amendment
No. 5") of Unitil Corporation (the "Company"), a New Hampshire corporation,  and
a registered  public utility  holding  company under the Public Utility  Holding
Company Act of 1935, and its subsidiaries,  Concord Electric  Company,  Exeter &
Hampton  Electric  Company,  Unitil Power Corp.,  Unitil  Realty  Corp.,  Unitil
Resources,  Inc.  and Unitil  Service  Corp.,  each of which is a New  Hampshire
corporation,  and its  subsidiary  Fitchburg  Gas  and  Electric  Light  Company
("Fitchburg"),  a Massachusetts corporation  (collectively,  the Company and its
subsidiaries are referred to as the "Applicants"). The Commission has issued two
earlier orders related to previous application-declarations filed under File No.
70-9633.  See Holding Co. Act Release Nos.  27182 (June 9, 2000) and 27307 (Dec.
15, 2000).

     In Post-Effective  Amendment No. 5, the Applicants request authorization to
raise the Company's permitted level of short-term  borrowing from $35 million to
$45 million and  Fitchburg's  permitted  level of short term  borrowing from $20
million to $30 million.

     We have examined originals of Post-Effective Amendment No. 5 and originals,
or copies  certified  to our  satisfaction,  of such  corporate  records  of the
Applicants,  certificates  of public  officials,  certificates  of officers  and
representatives  of the  Applicants  and other  documents  as we have  deemed it
necessary to require as a basis for the opinions hereinafter expressed.  In such
examination, we have assumed the genuineness of all signatures, the authenticity
of all documents submitted to us as originals and the conformity to the original
documents of all documents  submitted to us as copies.  As to any facts material
to our opinion, we have, when relevant facts were not independently established,
relied upon the aforesaid agreements,  instruments,  certificates and documents.
In addition,  we have examined such questions of law, as we considered necessary
or  appropriate  for  the  purpose  of  rendering  this  opinion.  Based  on the
foregoing,  and  subject to the final  paragraph  hereof,  we are of the opinion
that:

          (1)  All  state  laws  applicable  to the  transactions  described  in
          Post-Effective Amendment No. 5 will have been complied with.

          (2) The Company and Fitchburg are validly  organized and duly existing
          under  the laws of the  State of New  Hampshire  and  Commonwealth  of
          Massachusetts respectively.

          (3) The notes to be issued to banks by the  Company and  Fitchburg  in
          accordance with  Post-Effective  Amendment No. 5 are valid and binding
          obligations  enforceable in accordance  with their  respective  terms,
          subject to bankruptcy, insolvency, reorganization, moratorium or other
          similar laws now or hereafter in effect relating to creditors'  rights
          generally, and to general principles of equity,  regardless of whether
          such  principles  are  considered at a proceeding at law or in equity,
          and further subject to the  qualification  that the remedy of specific
          performance and injunctive and other forms of equitable  relief may be
          subject to certain  equitable  defenses and to the  discretion  of the
          court before which any proceeding therefor may be brought.

          (4) The  consummation of the transactions  proposed in  Post-Effective
          Amendment  No. 5 will not violate  the legal  rights of the holders of
          any securities issued by the Company or Fitchburg.

     The opinions expressed above in respect of the approval of the transactions
described  in  Post-Effective  Amendment  No.  5 are  subject  to the  following
assumptions or conditions:

          a. The  Commission  shall have duly  entered an  appropriate  order or
          orders  granting  and  permitting  Post-Effective  Amendment  No. 5 to
          become effective with respect to the short-term  borrowings  described
          therein.

          b. No act or event other than as described  herein shall have occurred
          subsequent  to the  date  hereof,  which  would  change  the  opinions
          expressed above.

     We  hereby   consent  to  the  use  of  this   opinion  as  an  exhibit  to
Post-Effective Amendment No. 5.

     We are not,  in this  opinion,  opining  on laws other than the laws of the
State of New Hampshire,  Commonwealth of  Massachusetts  and the federal laws of
the United States.

                                        Very truly yours,


                                        LeBoeuf, Lamb, Greene & MacRae, L.L.P.