Little is known of Robert Sneden's life before the Civil War. Small scraps of scattered evidence reveal that he was born in the Canadian maritime province of Nova Scotia in 1832, the great-grandson of a Loyalist who had fled New York at the end of the American Revolution. When he was eighteen years old, he moved with his parents and two siblings to the teeming metropolis of New York City. Once there, he apparently decided to become an architect and engineer, two professions that flourished in a city that kept up a never-ending demand for factories, public buildings, commercial structures, and housing.

     One of the regiments formed shortly after the assault on Fort Sumter on April 12, 1861 was the 40th New York Volunteers or Mozart Regiment, the name given the unit by Mayor Fernando Wood to recognize the Mozart Hall political faction of the city's Democratic party. Although he did not sign up as a soldier at first, Robert Sneden decided to do his part for the Union and got himself appointed as the regiment's assistant quartermaster, no doubt through social or business contacts. For whatever reason, he served as an unpaid civilian and did not officially join the army for several months. He recorded few details of his early war experience, but general comments he made later and other sources indicate that it was a time of both exhilaration and frustration.

     Finally word raced through the camp that it was time to head to the front. Excitement was intense. Mayor Fernando Wood and a large delegation of city officials traveled to Yonkers on July 3 to present the Mozarters with a beautiful silk flag surmounted by a gold eagle and emblazoned with the motto "E Pluribus Unum." Looking straight at the men, the mayor exclaimed: "If that flag falls, every man will fall with it; if it conquers, every man in the regiment will conquer with it. . . . It must never be humbled in the dust. We look to you for its defense, knowing that you will defend it to the last." The soldiers cheered lustily and were then formed up by their officers to show off their martial skills in a formal dress parade. The men then returned to camp and began preparing for the trip south.

     On July 7, when the Mozarters arrived in Washington by train, anxious to meet the enemy, Robert Sneden was not with them. Still a civilian, he stayed behind, charged with a sizable clean-up job at Yonkers. The regiment had left the camp a mess. Boxes, barrels, tin plates and cups, and clumps of straw littered the grounds. Sneden invited local residents to take whatever they wanted, and then he had the campground cleaned up to turn back over to its owner. He sold all of the surplus stores of foodstuff left behind and carefully prepared the paperwork to send to regimental headquarters, now in Virginia. Then for reasons that are not clear, Sneden traveled to Boston, possibly to sign up more recruits for the 40th New York, four companies of which already were composed of Massachusetts men. While there, he would have received the shocking news of the disastrous Union defeat at Bull Run in Virginia on July 21.

      Before the battle, many people on both sides had expected the war to be a short one. But in the aftermath of the first big action, it became evident that a quick conclusion of the conflict was no longer possible. Amateur armies had to be turned into the efficient fighting forces. In the North, a lust to avenge Bull Run caused a whole new wave of recruits to don the uniform of blue. No longer content to remain a civilian in the backwaters of the war, Robert decided to follow suit and join his comrades of the 40th New York, who had been kept out of the Bull Run battle but were drilling earnestly for the next fight.