The roar of the distant battle was incessant; the low, subdued, blended noise of the mingled small arms, with the frequent heavier bursts of cannon. 
Such was William Harrison Beach’s personal account of the Battle of Antietam (1862). In 1902, Beach published The First New York (Lincoln) Cavalry from April 19, 1861, to July 17, 1865. This eyewitness account was taken from several reliable sources: his own diary, (which he regularly kept throughout his four years as an officer in The First New York Cavalry), letters written home, as well as diaries and communications of his comrades. The result of these compilations is an intelligent, detailed picture of the Civil War through the eyes of cavalry men.
President Abraham Lincoln authorized the raising of The First New York Cavalry in 1861. It was the first call of a federally-approved volunteer cavalry, which was organized into 12 companies, with each company consisting of about 100 men. The regiment was commanded by a commissioned officer, Colonel Andrew T. McReynolds. Since ten of the twelve companies came from New York, (with Pennsylvania and Michigan furnishing the other two), the entire regiment was assigned to that state and was comprised of “worthy men and boys who promptly responded to the President’s first call for volunteers, or who rather anticipated a call for volunteer cavalry.” As a result, it became known as The Lincoln Cavalry.
In general, the cavalry’s role in the Civil War was to support the infantry and artillery by gathering intelligence, scouting, and disrupting the enemy’s communications and supply line. Additional duties included shoeing horses, re-tiring wagon wheels, and protecting the lines of transportation (such as the Baltimore & Ohio railroad) from ranging bands of soldiers. By the end of the war, the Federal (Union) cavalry had developed into a powerful, offensive force.
War records indicate that The First New York (Lincoln) Cavalry was present at the Battle of Antietam. Beach’s particular company or detachment, however, was not one of them. They heard the battle in the distance (as they passed over South Mountain) and arrived in Sharpsburg, Maryland, shortly after deadly silence had settled over the valley. Two days later, September 19, Beach would write:
The 19th the entire regiment marched out on the field. The dead men had been buried, but there were many dead horses swollen to an immense size. Many troops were on the field, massed in solid squares ready to renew the battle. But Lee had crossed the river.
Charles R. Peterson of Company B had a brother, Lieut. Pierson B. Peterson, adjutant of the Seventy-eighth N. Y., one of the new regiments that had just come to the front. He learned that this regiment had been engaged in the battle. In his search for the regiment he heard that his brother had been wounded. …In some woods along the roadside near Keedysville many hospital tents had been set up. In front of one of these was a hospital nurse inquiring for Peterson of Company B, saying that his brother was lying in the tent, his leg having been amputated. The younger Peterson was absent from the ranks still engaged in his tireless search. A man of the company was directed to remain here, to tell Peterson, when he should find him, that he could stay and take care of his brother. This was a considerate act on the part of Colonel McReynolds. The wounded lieutenant was tenderly cared for, but he slowly failed. Finally after a period of delirium in which he seemed to be again in the front of the battle, giving orders for the line to stand firm, and then to move forward, he passed away. …This sad meeting of brothers after the battle was one of many similar incidents of the war. 
The Battle of Antietam left a deep mark on The First New York Cavalry. In late September 1863, a year after the bloody conflict, Beach records that the entire regiment found themselves marching below the Shepherdstown ford, over the Antietam battlefield again.
“The men were interested in identifying the places over which they had moved the year before. …The men studied the situation of Antietam, the sunken road, the cornfield, Miller’s barn, the Burnside bridge.” 
Among this band of brothers was a wagoner of Irish descent. Private John Sullivan, my great-great grandfather.
The career of the regiment was not an unbroken succession of brilliant charges. Nor were the officers and enlisted men all knights ‘”without fear and without reproach.” But they did good service to the country, and the record of what they did, though imperfectly made up, deserves to be preserved.” 
 This photo by Civil War photographer, Alexander Gardner, is a “picture of a picture” that I took while visiting the Alexander Gardner exhibit on display at Antietam in 2012 to commemorate the 150th Anniversary of the Battle of Antietam. Gardner took this photograph just two days after the bloody Battle. Gardner’s visual documentation of the Civil War (over 70 preserved images) is both priceless and a graphic reminder of the stark realities of war.
 The First New York (Lincoln) Cavalry from April 19, 1861, to July 17, 1865 by William Harrison Beach, page 186.
 Ibid., pages 187-188.
 Ibid., page 294.
 Ibid., ix.