Garfield proved himself to be a capable military commander,
and demonstrated great courage and ingenuity. Once, when his brigade's
supplies ran low, Garfield made the trip for food himself, and ferrying
the food across a dangerous river by using his skills as a former
canal boat worker.
Garfield marched his men south to dislodge the final remnants
of Humphrey Marshall's forces, moving his men a grueling one hundred
miles in only four days. After this exploit, Garfield's troops joined
General Don Buell's army, and Garfield received command of the
Twentieth Brigade. Buell's army was present at the second day of
battle at Shiloh,
one of the bloodiest battles of the war.
While the Union army rested after its heavy losses at
Shiloh, Garfield received an order from the division commander
to have his men hunt down a runaway slave believed to be in the
area. Garfield refused to obey the order, despite the threat of
a court-martial, arguing that neither he nor his men had joined
the army to hunt slaves. In June, 1862, Garfield oversaw the rebuilding
of the bridges on the Memphis and Charleston railroad and helped
with the fortification of Huntsville; several colleagues observed
that he displayed a surprising knowledge of engineering considering
that he had never formally studied it. However, Garfield fell dangerously
ill from malaria before the war progressed much further and returned
to Ohio to recuperate.
When he returned home, Garfield found that he was a candidate for
Congress in his district. Even though Garfield had sought neither
the Republican nomination nor the seat in the general election, he
handily won the November election. It would be a while, however,
before Garfield actually took his seat in Congress. After recovering
at home, Garfield served on a court-martial panel for the military
in Washington, finding General Fitz-John Porter guilty of failing
to support the commanding general at the Second Battle of Bull
Run. While in Washington, Garfield reacquainted himself with former
Ohio Governor Salmon P. Chase, now the Secretary of the Treasury.
Throughout the years that followed and his later political career,
Garfield looked to Chase as a mentor.
In January 1863, the Army ordered Garfield to Murfreesboro, Tennessee,
where he served as chief of staff to General William S. Rosecrans.
Garfield oversaw the training of Rosecrans's army and the two men
became fast friends. When the days' work was finished, they often
debated literature and religion late into the night. While fighting
the forces of Confederate General Braxton Bragg in Tennessee, Rosecrans
overadvanced and was forced to retreat, leaving the Union army
of General George H. Thomas exposed. Garfield volunteered to carry
the notice of the retreat to Thomas and rode through heavy enemy
fire that downed two members of his party. Garfield arrived in
time to save Thomas's force from being flanked and he was promoted
to Major-General on September 19, 1863. Garfield would never use
this commission, however, for President Abraham Lincoln,
in need of intelligent and loyal Republican allies, asked Garfield
to take up his seat in Congress.