Garfield read military texts while anxiously awaiting the war effort, which he regarded as a holy crusade against the Slave Power.[34] In April 1861, the rebels bombarded Fort Sumter, one of the South's last federal outposts, beginning the Civil War. Although he had no military training, Garfield knew his place was in the Union Army.[34]
At Governor William Dennison's request, Garfield deferred his military ambitions to remain in the legislature, where he helped appropriate the funds to raise and equip Ohio's volunteer regiments.[35] When the legislature adjourned Garfield spent the spring and early summer on a speaking tour of northeastern Ohio, encouraging enlistment in the new regiments.[35] Following a trip to Illinois to purchase muskets, Garfield returned to Ohio and, in August 1861, received a commission as a colonel in the 42nd Ohio Infantry regiment.[36] The 42nd Ohio existed only on paper, so Garfield's first task was to fill its ranks. He did so quickly, recruiting many of his neighbors and former students.[36] The regiment traveled to Camp Chase, outside Columbus, Ohio, to complete training.