United Community Banks Inc. and Three Shores Bancorporation Inc. have said that they have entered into a definitive agreement under which UCBI will acquire Three Shores, including its wholly-owned subsidiary, Seaside National Bank Trust. Gideon Haymaker, president and chief executive officer of Three Shores, will become a key part of United's team and continue to lead the Florida market, following the completion of the transaction. Haymaker has more than 38 years of executive experience in regional banking.