Milledge L. Bonham received his early education in the “old field” schools of the neighborhood, and his academic training under instructors at Abbeville and Edgefield.  He entered the South Carolina College and graduated with second honor in 1834.  Soon thereafter the Seminole or Florida war broke out, and he volunteered in the company from Edgefield, commanded by Captain James Jones, and was Orderly Sergeant of the company.  During the progress of the war in Florida, he was appointed by General Bull, who commanded the South Carolina Brigade, to be Brigade Major, a position which corresponds with what is now known in military circles as Adjutant General of Brigade.

Returning from the war, he resumed the study of law and was admitted to the Bar and settled at Edgefield for the practice of his profession.  In 1844 he was elected to the Legislature.  He always took an ardent interest in the militia, and was first Brigadier General and afterwards Major General of militia.  When the war with Mexico was declared, he was appointed lieutenant Colonel of the Twelfth United States Infantry, one of the new regiments added to the army for that war.  With his regiment he went to Mexico and served with distinction throughout the war, being promoted to Colonel of the regiment, and having, by the way, for his Adjutant, Lieutenant Winfield Scott Hancock, afterwards a distinguished Major General of the Federal Army in the late war.  After the cessation of hostilities, Colonel Bonham was retained in Mexico as Military Governor of one of the provinces for about a year.  Being then honorably discharged, he returned to Edgefield and resumed the practice of law.  In 1848 he was elected Solicitor of the Southern Circuit, composed of Edgefield, Barnwell, Orangeburg, Colleton, and Beaufort Districts.  The Bars of the various Districts composing this Circuit counted among their members many of the ablest and most distinguished lawyers of the State, and hence it required the possession and industrious use of talents of no mean order to sustain one’s self as prosecuting officer against such an array of ability.  But General Bonham continued to hold the office until 1856, when, upon the death of Hon. Preston S. Brooks, he was elected to succeed that eminent gentleman in Congress, and again in 1858 was elected for the full term.  Those were the stirring times preceding the bursting of the cloud of civil war, and the debates in Congress were hot and spicy.  In all these he took his full part.  When South Carolina seceded from the Union, he promptly resigned his seat in Congress, and was appointed by Governor Pickens Commander-in-Chief of all the forces of South Carolina with the rank of Major General.  In this capacity, and waiving all question of rank and precedence, at the request of Governor Pickens, he served on the coast on Morris’ Island with General Beauregard, who had been sent there by the Provisional Government of the Confederacy to take command of the operations around Charleston.