Hodgson joined the Union forces in Brooklyn, New York, and on June 24, 1861, he was mustered in for three years as First Lieutenant, Company K, 67th NY Infantry. The regiment left New York on August 21, 1861, and became part of the Army of the Potomac for the duration of the war. As part of the 1st Division, 4th Corps, the 67th participated in the siege of Yorktown, VA, and the subsequent Battle of Williamsburg, but suffered no losses until the Battle of Fair Oaks, VA (May 31 - June 1, 1862).
month after leaving New York with the regiment, Hodgson reported the
following incident in a letter to his wife dated September
30, 1861: a soldier who had been relaxing in the woods heard a
comrade call to him. "On coming out of the little bower…he caught
his musket in a stick and it went off…shooting his comrade who was
walking sentry, in the right arm passing through the shoulder in the
chest and lodging between the clavicle & first rib, killing him
instantly." This was perhaps the first death Hodgson witnessed
during the war.