EXHIBIT 2.1

                        AMENDMENT TO AGREEMENT OF MERGER
                           AND PLAN OF REORGANIZATION

         This Amendment to Agreement of Merger and Plan of Reorganization (the
"Amendment") is made and entered into this 21st day of March, 2005 by and among
Horizon Bancorp, an Indiana corporation ("Horizon"), Horizon Acquisition Corp.,
an Indiana corporation ("Horizon Acquisition Corp."), Alliance Financial
Corporation, a Michigan corporation ("Alliance"), Horizon Bank, National
Association, a national banking association ("Horizon Bank"), and Alliance
Banking Company, a Michigan state-chartered commercial bank ("Alliance Bank").

         WHEREAS, the parties have previously entered into a certain Agreement
of Merger and Plan of Reorganization (the "Agreement") and the related
agreements dated February 24, 2005; and

         WHEREAS, the parties desire to amend the Agreement and some of the
related agreement and, as so amended, to reaffirm their mutual obligations
thereunder.

                                   WITNESSETH:

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants and conditions contained herein, the parties agree as follows:

         1. The $38.00 price per share for the Alliance Common Stock referred to
in Sections 1.6 and 1.7 of the Agreement (and in any other provision of the
Agreement) is changed to $42.50.

         2. All references to the $38.00 price per share in (i) the form of
Merger Agreement among Alliance and Horizon Acquisition Corp., which is attached
to the Agreement as Appendix A, (ii) the form of Agreement to Convert Options,
which is attached to the Agreement as Exhibit 1.7, and (iii) the form of
Agreement of Directors of Alliance Concerning Agreement of Merger, which is
attached to the Agreement as Exhibit 4.3 and the executed version of that
agreement dated February 24, 2005; are each similarly changed to $42.50.

         3. The termination fee (the "Fee") provided for in Section 7.11 of the
Agreement is changed to $1,000,000.

         4. The parties agree to execute a new form of the Merger Agreement
among Alliance and Horizon Acquisition Corp., which is attached to the Agreement
as Appendix A, reflecting the new $42.50 price per share for the Alliance Common
Stock.

         5. The following time periods described in the Agreement are hereby
extended by the number of days that elapse between March 10, 2005, and the date
that Alliance and its affiliates execute this Amendment: (i) the 45 day periods
referred to in Section 4.5 of the Agreement with respect to obtaining
environmental reports by Horizon and its ability to terminate the Agreement,
(ii) the 45 day period referred to in Section 4.9(a) of the Agreement with
respect to obtaining real estate title information by Horizon, and (iii) the 30
day period




referred to in Section 5.1 of the Agreement with respect to the filing of
applications and notices by Horizon with regulatory authorities.

         6. The parties hereto recognize and agree that capitalized terms used
in this Amendment and not otherwise defined herein, shall have the meanings
assigned to them in the Agreement, and except for the provisions of the
Agreement specifically or expressly amended by this Amendment, all other terms,
conditions, and provisions of the Agreement remain in full force and effect and
are hereby reaffirmed in their entirety.

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
Agreement of Merger and Plan of Reorganization to be executed on this 21st day
of March, 2005.

                                 HORIZON BANCORP

                                 By: /s/ Craig M. Dwight
                                     ----------------------------------------

                                 Title: President and Chief Executive Officer
                                        -------------------------------------

                                 HORIZON ACQUISITION CORP.

                                 By: /s/ Craig M. Dwight
                                     ----------------------------------------

                                 Title: Chairman and Chief Executive Officer
                                        -------------------------------------

                                 ALLIANCE FINANCIAL CORPORATION

                                 By: /s/ Joseph G. Migely
                                    -----------------------------------------

                                 Title: President
                                        -------------------------------------

                                 HORIZON BANK, NATIONAL ASSOCIATION

                                 By: /s/ Craig M. Dwight
                                     ----------------------------------------

                                 Title: Chairman and Chief Executive Officer
                                        -------------------------------------

                                 ALLIANCE BANKING COMPANY

                                 By: /s/ Joseph G. Migely
                                    -----------------------------------------

                                 Title: President
                                        -------------------------------------