Garfield sent a telegram to Secretary of War Edwin M. Stanton alerting Washington to the need for reinforcements to avoid annihilation. Lincoln and Halleck responded to the request for reinforcements by sending 20,000 troops to Garfield by rail within nine days.[65] In the meantime, Grant was promoted to command of the western armies and quickly replaced Rosecrans with George H. Thomas.[66] Garfield was ordered to report to Washington, where he was promoted to major general.[67] According to historian Jean Edward Smith, Grant and Garfield had a "guarded relationship" since Grant promoted Thomas, rather than Garfield, to command of the Army of the Cumberland after Rosecrans's dismissal.[68]

Congressional career[edit]
Election in 1862; Civil War years[edit]
Salmon P. Chase was Garfield's ally until Andrew Johnson's impeachment trial.
While he served in the Army in early 1862, friends of Garfield approached him about running for Congress from Ohio's newly redrawn and heavily Republican 19th district. He worried that he and other state-appointed generals would receive obscure assignments and running for Congress would allow him to resume his political career. 