The Grand Army of the Republic held national encampments annually from 1866 to 1949. Isaac attended a few of them. He also regularly attended state encampments in part due to his duties as the Ed Hamlin GAR Post Commander. Knowing Isaac, he would probably have attended these encampments whether or not he was the Post Commander. Isaac wrote a report on his experiences at one such state encampment held in Muscatine, Iowa.
16000 inhabitants Report of Muscatine State Encampment For June 13 14 & 15 1911
Lot Abraham of Mt Pleasant was Elected dpt Com [department commander?]
The booming of Cannon at Sunrise June 13th started the State Encampment the good people of Muscatine have been for weeks preparing for with a cool north breeze & a clear Sky it seems the weather man Saved his most Comfortable days for this occasion hundreds of the gar & wrc thronged the Streets & the first day fully 1500 had registered & drawn badges the very first arrivals found the City ready to rec them [with a] well organized reception
Committees handled the crowd in good Shape & the Pearl City was given over to the men who wear the little bronz button with many Autos at hand & a complete filing system all visitors were assigned to quarters without delay Muscatine is to day displaying the same patriotism it did in 61 when it sent the greatest body of fighting men to the front of any county in the State
B C Ward [Desmoines] SVC arrived in the city the first day & as H A Dyer our dpt Com of Mason City is Sick the SVC will preside at the meetings gov Carrol was present & made a fine talk but left for Desmoines after Staying one night the decorations were said to be more & better than at any State Encampment & the Cordiality displayed by the People made Evry one feel at home & the music the best I have heard for many yrs drums & fifes that went thru the war & the men who played them in those Stirring times still able to make the best of music & I noticed many old veterans dressed in the navy blue uniform with brass buttons & the campaign hat with cord & tassel
To be continued..
 Wikipedia: Grand Army of the Republic, https://en.wikipedia.org/wiki/Grand_Army_of_the_Republic
 Beryl Franklin Carroll, March 15, 1860-December 16, 1939) was Iowa’s 20th governor. His biography is found at http://uipress.lib.uiowa.edu/bdi/DetailsPage.aspx?id=56