Carter had entered the U.S. Army on September 26, 1941. As a result of his previous combat experience, he stood out among the other recruits. In less than a year, he had achieved the rank of staff sergeant. Carter was part of the 56th Armored Infantry Battalion of the 12th Armored Division. Provisional platoons of African-American troops were established in the wake of the Battle of the Bulge, which took place during the winter of 1944–1945. Black support and combat-support soldiers were allowed to volunteer for combat duty and were given brief training in small-unit tactics. Formed into provisional units, they were used to augment depleted divisions. Soldiers volunteering for this combat duty had to surrender their current rank. When the provisional companies were set up Carter volunteered and went from staff sergeant to private. On March 23, 1945, Carter, then a 28-year-old infantry staff sergeant, was riding on a tank when it was hit by a Panzerschreck. Dismounted, Carter led three soldiers across an open field. In the process, two of the men were killed and the other seriously wounded. Carter continued on alone and was wounded five times before being forced to take cover. Eight German soldiers tried to capture him, but he killed six and captured the remaining two. He used the two as human shields from enemy fire as he recrossed the field. His prisoners provided valuable information on enemy troop dispositions for his unit. For this, he was awarded the Distinguished Service Cross on October 4, 1945, and later promoted to sergeant first class. Carter was refused re-enlistment in Army in 1949, due to unfounded allegations that he had communist contacts and allegiances, related to his affiliation with the Abraham Lincoln Brigade and a "Welcome Home Joe" dinner. He died of lung cancer—attributed to shrapnel remaining in his neck—on January 30, 1963. Carter was buried at Los Angeles National Cemetery and re-interred at Arlington National Cemetery in 1997.
In the early 1990s, it was determined that black soldiers had been denied consideration for the Medal of Honor in World War II on ground of their race. In 1993, the Army contracted Shaw University in Raleigh, North Carolina, to research and determine if there was racial disparity in the review process for recipients of the Medal of Honor. A study commissioned by the Army described systematic racial discrimination in the criteria for awarding decorations during World War II. In 1996, after an exhaustive review of files, the study recommended that ten black Americans who served in World War II be awarded the Medal of Honor. In October of that year, Congress passed legislation that would allow the Medal of Honor to be passed to seven out of the ten former soldiers. The Medal of Honor was given to Carter's son, the descendants of the other five black Americans, and the only still-living recipient, Vernon Baker, on January 12, 1997. Out of the seven, six had their Distinguished Service Crosses revoked and upgraded.