When XII Corps was formed, Cothran’s battery was assigned to the division of Brigadier General Alpheus S. Williams.
Cothran returned in time for the Battle of Antietam, reporting for the battery's conduct in support of XII Corps at the north end of the battlefield near the East Woods.
At the time of the Mud March, the corps advanced to Stafford Court House, where it remained based until the spring of 1863.
[5] At the Battle of Chancellorsville, Winegar was in command of the battery once more, and it crossed the Rappahannock River on April 30, accompanying the advance of Williams’ division.
Battery M had yet to open fire on the Confederates when the corps was recalled to a defensive position in the Fairview clearing near the Chancellor house facing east.
[14] Captain Clermont L. Best, XII Corps chief of artillery, moved some of Winegar's guns on the night on July 2–3.
[5]) The battery took part in the cannonade that preceded a largely successful effort to recapture ground lost on July 2 when most of XII Corps was sent to the left flank of the army as reinforcements.
[6] Charles Winegar was promoted to the rank of captain on May 3, 1864, and he took command of Battery I, First New York Artillery with its six three-inch rifled guns.
[18] (Captain Michael Wiedrich had been assigned to a heavy artillery regiment; and Nicholas Sahm, his successor, had died.)
It was assigned to Williams' division until all XX Corps batteries were combined into an artillery brigade under Major John A. Reynolds during the Atlanta Campaign.
His battery was seriously involved in support of Williams' division on the left flank of Sherman's army in the Battle of Resaca on May 13, 1864, helping repel an assault by Lieutenant General John B.
[21] Battery I played a significant role in the Battle of Kolb's Farm on June 22, being credited by Major Reynolds with doing damage to a Confederate attack on XX Corps.
At the Battle of Peachtree Creek on July 20 Winegar's guns were used to good effect at two places on the Union line against the Confederate assault on the Army of the Cumberland.
[25] When Sherman gambled on flanking Hood out of Atlanta in late August, XX Corps fell back to the Chattahoochee to defend the Union supply line.
In October, Colonel Daniel Dustin took much of third division XX Corps plus artillery and cavalry foraging east of Decatur, Georgia.
[28] When Sherman left Atlanta on November 15, XX Corps was part of the column Major General Slocum led in the March to the Sea, what later was called the Army of Georgia.
[29][7] Four days later, Battery I was moved to Argyle Island to deal with harassment of Colonel Ezra Carman's brigade by Confederate guns.
[8] In the latter fight, Battery I played a significant role in repelling the attack of Major General William B. Bate from its position near the Goldsboro Pike.
[32] Late in the war, on April 1, 1865, as Sherman moved northward toward Raleigh, North Carolina, Captain Winegar took command of the artillery brigade of XX Corps after Major Reynolds left the army on leave.