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     As filed with the Securities and Exchange Commission on June 17, 2002
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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                                   SCHEDULE TO
             Tender Offer Statement under Section 14(d)(1) or 13(e)
                     Of the Securities Exchange Act of 1934
                                (AMENDMENT NO. 5)

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                               TRENWICK GROUP LTD.
                       (Name of Subject Company -- Issuer)

                               TRENWICK GROUP LTD.
                       (Name of Filing Person -- Offeror)

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          OPTIONS TO PURCHASE COMMON SHARES, PAR VALUE $.10 PER SHARE,
           ISSUED UNDER THE TRENWICK GROUP INC. 1989 STOCK PLAN, THE
          TRENWICK GROUP INC. 1993 STOCK OPTION PLAN, THE CHARTWELL RE
              CORPORATION 1993 STOCK OPTION PLAN, THE CHARTWELL RE
             CORPORATION 1997 OMNIBUS STOCK INCENTIVE PLAN AND THE
           LASALLE RE HOLDINGS LIMITED 1996 LONG-TERM INCENTIVE PLAN
                         (Title of Class of Securities)

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                                 JOHN V. DEL COL
                                    SECRETARY
                               TRENWICK GROUP LTD.
                              CONTINENTAL BUILDING
                                25 CHURCH STREET
                             HAMILTON HM 12, BERMUDA
                             TELEPHONE: 441-292-4985
                             FACSIMILE: 441-292-2656
      (Name, address and telephone number of person authorized to receive
             notices and communications on behalf of Filing Person)

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                                   A COPY TO:
                                JAMES R. CAMERON
                                BAKER & MCKENZIE
                                 805 THIRD AVE.
                            NEW YORK, NEW YORK 10022
                             TELEPHONE: 212-891-3930
                             FACSIMILE: 212-891-3835



Check the appropriate boxes below to designate any transactions to which the
statement relates:

|_|  third-party tender offer subject to Rule 14d-1.
|X|  issuer tender offer subject to Rule 13e-4.
|_|  going-private transaction subject to Rule 13e-3.
|_|  amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: |_|

      This Amendment No. 5 amends and supplements the Tender Offer Statement on
Schedule TO, dated May 16, 2002, as amended by Amendment No. 1, Amendment No. 2,
Amendment No. 3 and Amendment No. 4 (the "Tender Offer Statement") filed by
Trenwick Group Ltd., a Bermuda corporation ("Trenwick"), relating to the offer
by Trenwick to exchange outstanding employee options to purchase its common
shares granted under the Trenwick Group Inc. 1989 Stock Plan, the Trenwick Group
Inc. 1993 Stock Option Plan, the Chartwell Re Corporation 1993 Stock Option
Plan, the Chartwell Re Corporation 1997 Omnibus Stock Incentive Plan and the
LaSalle Re Holdings Limited 1996 Long-Term Incentive Plan for new options to
purchase its common shares, upon the terms and subject to the conditions set
forth in the Offer to Exchange, which was attached to the Tender Offer
Statement, as Exhibit 99.2, as amended.

      This Amendment adds as an Exhibit the form of statement to be sent to
employees confirming their participation in the Offer.

Item 12. EXHIBITS.

      Item 12 to Trenwick's Schedule TO is hereby amended to add the following
Exhibit, which is filed with this Amendment No. 5 to Schedule TO:

      99.12 Form of Stock Option Program Election Confirmation Statement.



                                    SIGNATURE

      After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this Amendment No. 5 to Schedule TO is true,
complete and correct.

Dated: June 17, 2002

                                        TRENWICK GROUP LTD.


                                        By:      /s/ John V. Del Col
                                            -----------------------------------
                                            Name: John V. Del Col
                                            Title: Secretary