During the War of 1812 he fought on the side of the United States despite his advanced age. He participated in the Battle of Fort George in 1813, and in the Battle of Lundy's Lane in 1814. Following that battle a story is related that an Indian allied with the British (variously Chippewa or Mohawk) came to the Seneca saying he was deserting. He was identified as a spy, and Farmer's Brother said to him "here are my rifle, my tomahawk, and my scalping knife: take your choice by which you will die." The spy chose the rifle and indicated he wanted to be shot through the heart (or head), so Farmer's Brother immediately pointed his rifle there and killed him.