He was the designer of the 1824 Alamo Flag. "I have had a flag made," he wrote Stephen F. Austin on October 27, 1835, "the colours, and their arrangement the same as the old one-with the words and figures, `Constitution of 1824,' displayed on the white, in the centre."http://www.tshaonline.org/handbook/online/articles/fdi19
Dimmitt arrived at Bexar about January 24 with about thirty volunteers to reinforce the Alamo and was appointed army storekeeper; his warehouse at Dimitt's Landing then served as a depot for government stores landed at Lavaca Bay. Though many of the volunteers returned home upon the arrival of William B. Travis and his men on February 3, Dimmitt remained in San Antonio scouting for Travis and James Bowie until February 24.
Dimmitt's love for his country was evident even in his children's names, which included Antonio Alamo Dimmitt and Texas Philip Dimmitt. In 1858 Dimmit County was established and named in his honor