 After Abraham Lincoln 's election as president , several Southern states announced their secession from the Union to form a new government , the Confederate States of America . Garfield read military texts while anxiously awaiting the war effort , which he regarded as a holy crusade against the Slave Power . In April 1861 , the rebels bombarded Fort Sumter , one of the last federal outposts in the South , beginning the Civil War . Although he had no military training , Garfield knew that his place was in the Union Army . 
