John B. DuMaresq was born around 1839 in Ohio, possibly to British immigrant John DuMaresq and Margaret MacKay. DuMaresq enlisted in the Union army on August 9, 1862, and mustered in as a private in Company H of the 100th Ohio Infantry on September 1. He was captured at Limestone Station, Tennessee, on September 8, 1863, and spent the next two months imprisoned in Richmond, Virginia. He died there on November 18, 1863.