Forlorn Hope by Don Troiani. The 1st Maine Heavy Artillery in their charge at Petersburg.
The 1st Maine Heavy Artillery at Petersburg
The 1st Maine Heavy Artillery lost more men in a charge on Confederate lines during the Second Battle of Petersburg, June 18, 1864, than any other regiment in the entire war. Out of 900 men who made the charge 632 had been lost, with 7 officers and 108 men killed and 25 officers and 464 men wounded. They suffered a casualty rate of 67% - not the highest percentage of the war, but they lost a greater number of men than any other regiment in a single battle. The 1st Maine Heavies also suffered the greatest number killed throughout its service than any other Union regiment, with 423 killed out of an enrollment of 2,202.
They had only fought from 1864-65, having seen garrison duty in the defenses outside Washington until they were sent to the front in 1864. They first 'saw the elephant' at Spostsylvania, losing heavily in their first action there, and serving throughout the rest of the Overland Campaign on through Petersburg.
Save the Colors by Keith Rocco. The 5th New York "Duryee's Zouaves" at Second Manassas.
5th New York Duryee's Zouaves at Second Manassas
On August 30, 1862, the 5th New York Volunteer Infantry "Duryee's Zouaves" were infamously decimated in their stand against Hood's Texas Brigade, holding off Longstreet's attack on Pope's flank.
It was a suicide mission, but as one of the best-drilled regiments in the Army of the Potomac the Zouaves were determined to stand their ground. Positioned on an open hill top and outlined against the sky in their red uniforms, they were struck from front and both flanks by three regiments of the Texas Brigade, pouring fire into their ranks. Before the 5th New York could put up a fight for long their ranks were already torn to shreds by the converging fire. "Where the Regiment stood that day was the very vortex of Hell," Pvt. Andrew Coats remembered; "Not only were men wounded, or killed, they were riddled." Col. Warren ordered the survivors to break for the rear. "I saw my comrades dropping on all sides," Pvt. Alfred Davenport wrote, "canteens struck and flying to pieces, haversacks cut off, rifles knocked to pieces; it was a perfect hail of bullets." In under eight minutes 330 of the 500 Zouaves engaged were casualties, 120 of them dead or dying - the highest fatality rate suffered by any Federal infantry regiment in the war, not counting heavy artillery.
The Boy Colonel by Don Troiani. Colonel Henry King Burgwyn, Jr., commanding the 26th North Carolina Infantry at Gettysburg.
The 26th North Carolina at Gettysburg
On the first day of the Battle of Gettysburg, the 26th North Carolina was locked in a vicious stand-up fight against the 24th Michigan of the Iron Brigade in Herbst's Woods on McPherson's Ridge. Though the Iron Brigade was eventually driven back, the 26th North Carolina suffered heavy losses. The regimental colors were shot down fourteen times; the regimental commander Colonel Henry King Burgwyn, Jr., was killed; and his second-in-command, Lt. Col. John R. Lane, was seriously wounded. On July 3 the 26th NC would also take part in the charge on Cemetery Ridge, suffering even more losses. Out of 820 men engaged at Gettysburg, 588 men were killed, wounded, or missing, for 71.7%. It was not the highest percentage, but the 26th NC lost more men in number than any other Confederate regiment in the war.
Edit: The losses I listed for the 26th NC were only for the first day. I got the numbers from William F. Fox's Regimental Losses. According to Covered with Glory by Rod Gragg, the 26th had 800 officers and men engaged and lost 588 on July 1 and 99 on July 3, for a total of 687, or 86%.
Lone Star by Don Troiani, depicting the 1st Texas Infantry fighting through Miller's Cornfield.
1st Texas at Antietam
The 1st Texas Infantry of Hood's Texas Brigade charged into Miller's Cornfield at Antietam on the morning of Sept. 17, 1862. They first slammed into the Iron Brigade, driving them through the cornfield. They kept going until they reached the northern edge of the field, where Anderson's brigade of Meade's division was posted. There, they were caught in a cross fire from several Pennsylvania regiments to their front and Campbell's Battery to their left. Though they fought like hell, 186 of their 226 men engaged were killed or wounded; the entire color guard was also shot down and both of their colors lost in the cornfield. The 1st Texas' loss of 82.3% was reportedly the highest casualty rate suffered by any Confederate regiment in the war.
Edit: note that Col. Philip A. Work later wrote in an 1891 letter that on the evening of Sept. 16, two men from each of the twelve companies were detailed for foraging. Only nine of them returned to the regiment by following morning, so it actually went into action with only 211 officers and men. With a loss of 186 (50 killed, 132 wounded, ad 4 missing), the 1st Texas’ actual casualty percentage was 88%.