Title: Society of the Army of the Potomac Twenty-first Annual Reunion
Publisher: Macgowan and Slipper, New York
Date Published: 1890
Keywords: Joshua Chamberlain, Lawrence Chamberlain, Joshua Lawrence Chamberlain,
Permissions: public domain
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The Twenty-first reunion of the Society of the Army of the Potomac
Portland, Maine July 3, 1890

Chamberlain was president of the society the previous year in New Jersey and had helped to sway the vote for the next to be held in Maine, this is evidenced in Holman Melcher's speech on page 12.

Francis Walker's speech on page 18 is also worth a glance. Did Chamberlain possibly use this when composing his own speech "The Last Review of the Army of the Potomac?"
For a mention of this reunion in the New York Times visit their site: nytimes.com