Governor Dennison appointed Garfield colonel of the Forty-second Ohio Regiment, and he left the Senate for the battlefield, nearly one hundred Hiram students enlisting under him. At once he began to study military tactics in earnest. He organized a school among the officers, and kept the men at drill till they were efficient in the art of war. January 10, 1862, he fought the battle of Middle Creek, with eleven hundred men, driving General Marshall out of Eastern Kentucky, with five thousand men. The battle raged for five hours, sometimes a desperate hand-to-hand fight. General Buell said in his official report of Garfield and his regiment: "They have overcome formidable difficulties in the character of the country, the condition of the roads, and the inclemency of the season, and, without artillery, have in several engagements, terminating in the battle of Middle Creek, driven the enemy from his intrenched positions and forced him back into the mountains, with the loss of a large amount of baggage and stores, and many of his men killed and captured. These services have called into action the highest qualities of a soldier--fortitude, perseverance, and courage." After this battle, President Lincoln made Garfield a brigadier-general. Says Mr. Bundy: "Having cleared out Humphrey Marshall's forces, Garfield moved his command to Piketon, one hundred and twenty miles above the mouth of the Big Sandy, from which place he covered the whole region about with expeditions, breaking up rebel camps and perfecting his work. Finally, in that poor and wretched country, his supplies gave out, and, as usual, taking care of the most important matter himself, he went to the Ohio River for supplies, got them, seized a steamer, and loaded it. But there was an unprecedented freshet, navigation was very perilous, and no captain or pilot could be induced to take charge of the boat. Garfield at once availed himself of his canal-boat experience, took charge of the boat, stood at the helm for forty out of forty-eight hours, piloted the steamer through an untried channel full of dangerous eddies and wild currents, and saved his command from starvation." Later, Garfield became chief of General Rosecrans' staff, was in the dreadful battle of Chickamauga, and was made major-general "for gallant and meritorious services" in that battle. Rosecrans said: "All my staff merited my warm approbation for ability, zeal, and devotion to duty; but I am sure they will not consider it invidious if I especially mention Brigadier-General Garfield, ever active, prudent, and sagacious. I feel much indebted to him for both counsel and assistance in the administration of this army. He possesses the energy and the instinct of a great commander."