Wilkes Walker is a convict and former NCR Army sergeant sent out into the Denver Wasteland as part of the NCR's Project Cook. He is currently the project's head of the scavenging operations.
Background
Early life
Wilkes was born was born on the 1st of July 2258 in the Hub, one of the largest settlements on the western side of the American wasteland. As the son of a merchant family, he spent most of his youth on the streets of the city, inevitably becoming involved in violence and petty crime. He was not intent on living that life forever, though, so as soon as he came of age, he enlisted in the NCR Army - around the same time his childhood rival and enemy, Tom Perton, who had gotten in many a fight with Wilkes, did.
Enlistment
During the training period, Wilkes showed a particular knack for rigging explosives and setting up booby traps. This made it an easy decision for his superiors to assign him to a sabotage unit when the training was over. This squad, seeing as sabotage units were scarce among the NCR, saw a fairly large amount of action, and thus Wilkes soon became quite an experienced soldier. However, he had a hard time obeying the orders of his sergeant and other superiors, especially in the early stages of his career, and this kept him at a low rank for a long time. Perton, in the meantime, steadily started rising through the ranks through a combination of flattery and bribery.
In the years that followed, Wilkes turned out to be a strong-willed leader. This was both a blessing and a curse: his squad mates followed him with zeal, but when they messed up, he would carry out harsh repercussions. This went so far that at one point, he sent a soldier to retrieve dogtags from a radiation zone without protection, leaving him with severe radiation sickness. Insubordinate troopers also felt the butt of his rifle on more than one occasion. His abusive behaviour was an important contributive factor in the fact that he never made it past the rank of Sergeant.
Convoy fiasco and imprisonment
Roughly a year after the Second Battle of Hoover Dam, Wilkes' squad was part of an operation that was to establish a foothold for the NCR in Arizona. A convoy of troopers was on its way to there, but before they could pass through to the Arizona Wasteland, they had to get past a fortified position controlled by Caesar's Legion. In order to take out this position, Wilkes and his squad would sneak in, plant explosive charges, and then blow up the tower, so the convoy could pass safely. The mission started off smoothly, but after they had successfully planted the charges, the squad was discovered and got pinned under heavy fire. In the meantime, the convoy was nearly getting into the range of the tower's weaponry. In the heat of the moment, Wilkes saw no other choice than to escape the blast zone on his own, leaving his squad to perish - a tough decision, but a necessary sacrifice for the success of the mission.
After the mission, Tom Perton, who had by now become a Colonel, caught wind of Wilkes' act. Ever the petulant manchild, he decided to take advantage of the situation by slandering Wilkes and accusing him of intentionally killing his squad, arguing that he had abused his underlings before and that something like this was bound to happen. The slander campaign ended up in a court-martial for Wilkes. Since Perton had far more influence among the higher-ups of the army, it took very shortly before the decision was made to sentence Wilkes for life.