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                                                                     EXHIBIT 4.3

      THIS SECOND SUPPLEMENTAL INDENTURE, dated as of December 15, 2004, is
between CNA FINANCIAL CORPORATION, a Delaware corporation (the "Company"), and
J.P. MORGAN TRUST COMPANY, NATIONAL ASSOCIATION (formerly known as THE FIRST
NATIONAL BANK OF CHICAGO), a national banking association, as trustee (herein
called the "Trustee").

                              PRELIMINARY STATEMENT

      The Company and the Trustee have entered into an Indenture, dated as of
March 1, 1991, as supplemented by a First Supplemental Indenture, dated as of
October 15, 1993 (collectively, herein called the "Indenture"). Capitalized
terms used herein, not otherwise defined herein, shall have the meanings given
them in the Indenture.

      Section 8.1 of the Indenture provides that, under certain circumstances, a
supplemental indenture may be entered into by the Company and the Trustee
without the consent of any Holders of Securities. In accordance with the terms
of Section 8.1(d) of the Indenture, the Company has, by Board Resolution,
authorized this Second Supplemental Indenture. The Trustee has determined that
this Second Supplemental Indenture is in form satisfactory to it.

      All things necessary to make this Second Supplemental Indenture a valid
agreement of the Company and the Trustee and a valid amendment of and supplement
to the Indenture have been done.

      NOW, THEREFORE, THIS SECOND SUPPLEMENTAL INDENTURE WITNESSETH:

      For and in consideration of the premises, it is mutually covenanted and
agreed, for the equal and proportionate benefit of all Holders of the Securities
issued under the Indenture from and after the date of this Second Supplemental
Indenture, as follows:

   1. Article Five, Section 5.1(e) will be modified by replacing each occurrence
of the dollar amount of "$20,000,000" with the dollar amount of "$100,000,000".

   2. This Second Supplemental Indenture does not modify the Indenture in any
respect with regard to Securities issued thereunder prior to the date of this
Second Supplemental Indenture, and such Securities will not be modified by this
Second Supplemental Indenture.

      This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.

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      IN WITNESS WHEREOF, the Company and the Trustee have caused this Second
Supplemental Indenture to be duly executed by their respective officers
thereunto duly authorized and the seal of the Company and the Trustee duly
attested to be hereunto affixed all as of the day and year first above written.

                                           CNA FINANCIAL CORPORATION

[SEAL]                                     By:  /s/ Robert M. Mann
                                               ---------------------------------
                                           Name:    Robert M. Mann
                                           Its:     Senior Vice President

                                           J. P. MORGAN TRUST COMPANY, NATIONAL
                                           ASSOCIATION, as Trustee

[SEAL]                                     By:  /s/ Renee Johnson
                                               ---------------------------------
                                           Name:    Renee Johnson
                                           Its:     Vice President

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STATE OF ILLINOIS       )
                        ) ss.:
COUNTY OF COOK          )

      On the 15th day of December, 2004, before me personally came Robert M.
Mann, to me known, who, being by me duly sworn, did depose and say that he
resides at Chicago, Illinois; that he is the Senior Vice President of CNA
FINANCIAL CORPORATION, the corporation described herein and that executed the
above instrument; that he knows the seal of said corporation; that the seal
affixed to said instrument is such corporate seal; that it was so affixed by the
Board of Directors of said corporation and that he signed his name thereto by
order of the Board of Directors of said corporation.

      IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official
seal the day and year in this certificate first above written.

[NOTARIAL SEAL]
                                                 /s/ Susan C. Coghlan
                                                --------------------------------
                                                 Notary Public

<PAGE>

STATE OF ILLINOIS       )
                        ) ss.:
COUNTY OF COOK          )

      On the 15th day of December, 2004, before me personally came Renee Johnson
to me known, who, being by me duly sworn, did depose and say that he resides at
Chicago, Illinois; that he is a Vice President of J. P. MORGAN TRUST COMPANY,
NATIONAL ASSOCIATION, a national banking association, described herein and that
executed the above instrument; that he knows the seal of said corporation; that
the seal affixed to said instrument is such corporate seal; that it was so
affixed by the Board of Directors of said corporation and that he signed his
name thereto by order of the Board of Directors of said corporation.

      IN WITNESS WHEREOF, I have hereunto set my hand and affixed my official
seal the day and year in this certificate first above written.

[NOTARIAL SEAL]
                                                 /s/ Rebekah S. Cole
                                                --------------------------------
                                                 Notary Public