John Hinsch was born on April 11, 1831, in Riga in present-day Latvia. He immigrated to America around April 1848 and settled in Boston, Massachusetts. He petitioned for naturalization around 1858. By the late 1850s, he was working as a mariner in Gloucester, Massachusetts, and in May 1859, he received a seaman’s protection certificate.
He enlisted in the Union army, and he mustered in as a private in Company D of the 32nd Massachusetts Infantry on November 15, 1861. According to his service records, he was 5 feet, 7 ½ inches tall, with light hair and blue eyes. He received a series of promotions: first to sergeant, then to 2nd lieutenant in early 1863, and finally to 1st lieutenant in November 1863. The regiment took part in the Second Battle of Manassas, the Battle of Antietam, the Battle of Fredericksburg, the Battle of Gettysburg, the Overland Campaign, and the siege of Petersburg. He mustered out on December 1, 1864, and he died sometime afterward.