Born in 1925, James Buchanan Barnes lost both his parents early in his life; his mother had died when he was a child and his father had died in an accident while in basic training at Camp Lehigh shortly before Christmas in 1937. He was separated from his younger sister Rebecca, who was sent to boarding school while he persuaded officials into letting him remain at Camp Lehigh as a ward of the state due to sharing his father's love of the armed forces. He was eventually considered the camp mascot. During World War II, he set up a profitable endeavor providing soldiers with various non-requisition supplies. He soon began to receive select assignments as a special military operative, having received hand-to-hand combat training with British Commandos under the tutelage of William Essart Fairbairn and Colonel Rex Applegate. It was possibly linked to operations conducted by the mysterious Romulus, a figure involved in worldwide espionage. He met and befriended a young and somewhat naive private Steven Rogers, who had recently become the government operative Captain America. He was assigned to accompany Rogers, but was initially unaware of the true nature of his work. One night, Barnes happened into Rogers' tent just as he was changing to his masked identity. Sworn to secrecy, Barnes joined Captain America on his first mission against the Red Skull (Johann Schmidt), freeing many Nazi prisoners. For several months afterward, Barnes underwent an intensive training program under Captain America's tutelage. When he finished, he received his own costumed identity as Bucky and was designated as a counter-example to Hitler Youth. Although he was able to work with his mentor for most of his missions, James was trained to carry out missions the government officials did not want Captain America to be openly involved in. He was cynical and slightly dubious of the idealistic Steve Rogers, but they soon became the closest of friends.
When America entered World War II after the bombing of Pearl Harbor in December 1941, Captain America and Bucky abandoned their military identities for most of the war to devote their full energies to serving as costumed freedom fighters. They soon found themselves allied with the Sub-Mariner, the original Human Torch, and his young mutant partner Toro, in a team that Winston Churchill dubbed the Invaders. Bucky served Captain America and the Invaders capably and faithfully, leaving the team only temporarily in 1942 to organize and lead his own team of teenage soldiers, the Kid Commandos. Once, to rescue the Invaders from the Red Skull, Bucky assembled a team of costumed super-humans who operated on the home front, a group that would remain together until the end of the war and was known as the Liberty Legion He also worked with another group of teenagers, the Young Allies.
In late 1945, toward the end of the war, Captain America and Bucky were in London, England, on the trail of Nazi scientist Baron Heinrich Zemo. They discovered Zemo in the process of stealing an experimental drone plane built by the Allies. In the ensuing battle with Zemo's powerful humanoid robot, both Captain America and Bucky were rendered unconscious and strapped to the drone plane to be delivered to Hitler in Berlin. Unable to stand the sight of their patriotic costumes, Zemo dressed them in U.S. Army uniforms. Managing to escape before Zemo activated the plane, the two American champions saw the drone plane begin to move just as they jumped off. Quickly, Captain America and Bucky grabbed a motorcycle and tried to catch up with it. Just before it flew out of reach, the two leaped for the plane. Bucky leaped first and managed to get a grip on the plane's wing. Captain America missed, and shouted to his partner to let go in case the plane was booby-trapped. Bucky was unable to comply with his partner's commands because his uniform sleeved snagged onto the cockpit of the plane. The plane exploded, seemingly killing Bucky instantly. Captain America plunged into the English Channel to undergo the process of suspended animation, but Bucky's remains were never recovered strengthening the belief that he was killed in action.
As the Winter Soldier
James however was very much alive. When he had failed to disarm the plane in time he had leaped off of the plane but did not escape completely unscratched. The explosion had claimed his entire left arm. He then plunged into the icy waters only to undergo the same process his mentor had. After the war had ended, a Russian submarine hoping to recover and capture the missing Captain America (Steve Rogers) instead found the preserved body of Bucky. After being retrieved and examined for any traces of the Super Soldier serum, his body was placed in cryostasis.
In 1954, he was revived and outfitted with a replacement bionic arm which had been made after a Soviet spy had recovered schematics for cybernetic appendage. The arm was to be replaced by a newer and more advanced one every time there was an improvement in their technology. While he had no memory of his past, Barnes still had considerable physical skill. He was indoctrinated to hate the West and was provided with mental implants during sensory deprivation, molding him into the perfect assassin. It was during this period that he met Natasha Romanoff, whom he helped train in combat while she was undergoing espionage training. They fell in love and James often snuck into her sleeping quarters just so he could see her. Although Natasha was promised to Alexi Shostakov, she loved James more. This relationship did not last. Natasha learned that when Barnes was not needed for an operation or assassination he was kept in cryostasis in order to cease his aging.
He used to conduct many strategic assassinations across the world and would sometimes stay in one nation for extended periods. One of his targets was Itsu, the pregnant wife of his wartime ally Logan. However, after one of his missions, Barnes did not report back on time. He went off the grid in New York City. He was recovered at a flop house, where coincidently his former teammate Namor was also sleeping. As both men had amnesia, neither man recognized the other.
In 1983, he was assigned to accompany Vasily Karpov, an elderly general that had served in WWII, as bodyguard. He maintained the position until the general's death five years later. Barnes had demonstrated mental instability in some of his later missions and was placed into stasis at one of Karpov's storage facilities which had been inherited by his protégé, General Aleksander Lukin. Following the USSR's collapse, Lukin went rogue and established the Kronas Oil Corporation.
In order to seize the Red Skull's new Cosmic Cube, General Lukin reactivated Barnes to assassinate the Skull, although neither of them realized the Red Skull had simultaneously transferred his consciousness into Lukin's body. After assassinating the adventurer Nomad (Jack Monroe) and framing him for the Skull's assassination, Barnes detonated a fire bomb in Philadelphia which claimed many victims. Their deaths helped power the Cosmic Cube, but Lukin who had been disturbed by the Cube's effect gave it to Barnes to store in a nuclear-safe vault in West Virginia. During investigations by Nick Fury and S.H.I.E.L.D., Captain America (Steve Rogers) discovered the true identity of the Lukin's assassin and confronted him at the vault. The two engaged in combat until Rogers gained possession of the Cube and used its powers to restore James' lost memories. Overcome with remorse, Barnes used the cube to teleport away and went underground to search for Lukin and the Red Skull, still unaware that they were now one and the same.
After a confrontation with the now X-Man Wolverine in Serbia, Barnes managed to track Lukin to England where the Skull unleashed a sleeper robot, salvaged from the Eisendorf excavation. Barnes abandoned his initial intentions to seek and eliminate Lukin to aid Rogers in destroying the robot. This was the first time in over half a century that they worked together, but he fled afterwards unable to face his mentor. He was revealed to be an undercover operative working for Nick Fury, who had gone underground after leaving SHIELD. Barnes encountered the Young Avengers Patriot, Hawkeye, and Vision on one of his assignments and learned how his and Cap's adventures had inspired contemporary heroes. He also reconciled with his former Invaders teammate Namor, assisted Wolverine with incapacitating his son Daken, and comforted a cynical Patriot (Elijah Bradley).
Following Captain America's assassination, Barnes resolved to kill the two men he held responsible: the Red Skull and current S.H.I.E.L.D. Director Tony Stark (Iron Man). He acquired Cap's indestructible shield after defeating Black Widow, his former lover and student, in combat when she was assigned to move it to another location. Barnes then tracked Lukin and eventually confronted him only to discover his quarry was not a lead, but the Red Skull himself. Eventually captured by the Skull's forces, he resisted brainwashing by Dr. Faustus and was rescued by Falcon with the help of Sharon Carter, who was pretending to still be under Faustus' control. Barnes was then placed into SHIELD custody, but escaped and confronted Stark. He disabled his armor and fought him to a standstill only to learn his mentor's final requests of Stark: to rescue Barnes from his descent into violence and insanity, and to pass the Captain America identity to a successor. Stark felt the best way to honor both his friend's requests was for Barnes to become Captain America. Barnes agreed on the provision that his mind be cleansed of any remaining mental implants, and that he would answer to no one, not even Stark and S.H.I.E.L.D.
As Captain America
Now residing in Steve Rogers S.H.I.E.L.D. safe house, he outfitted himself with an alternate version of Cap's costume built by Tony Stark and, carrying his indestructible shield along with other weapons, Barnes quickly reacted against the efforts by the Red Skull and his accomplices to spread panic. Although effective in battle, he had yet to win the support or respect of either the US government or the general public. A number of civilians and costumed adventurers also disapproved of his current wardrobe; especially Clint Barton (Ronin, A.K.A Hawkeye). Despite the negative attention Barnes received, he continued to fight terrorism as Captain America and was often aided by Falcon (Sam Wilson), despite his initial disapproval of him. Together the two fought an A.I.M. cell headed by Arnim Zola. The Red Skull did not remain quiet for long. He responded to Barnes' meddling by sending the Grand Director, whose mind had been molded by Doctor Faustus to believe he was Steve Rogers and Captain America after him; James barely survived the confrontation, and was forced by Falcon to retreat. The two investigated the Grand Director's next course of actions after he escaped from the Skull's grasp and was becoming mentally unstable; most of it was hiding and running from detection by A.I.M. and the Red Skull. James was finally recognized by United States government and the public as hero after foiling an assassination attempt on both Republican and Democratic candidates for political debates by Sin, daughter of the Red Skull. He also revamped his relationship with the Black Widow, one of his few remaining friends who is consistently faithful to him. It was not long before he became involved in major conflicts such as an Invasion by extraterrestrial Skrulls along many other superheroes in New York. Wanting to continue to living his predecessor's legacy, James invited Clint Barton and the New Avengers to his safe-house, offering it as their base of operations as well as his own allegiance to their cause.
Although he was reformed, there were still a few officials from both America and other foreign nations who had not all forgotten his past as the Winter Soldier.
Captain America: Reborn
Bucky found out from Sharon that she had not really killed the original Captain America. As explained by Doctor Zola to Osborn, Rogers was trapped in a fixed position of time and space. But since Sharon ruined the machine that was suppose to bring him back, Steve was reliving his own past. Bucky and Black Widow attempted to steal the device from H.A.M.M.E.R, but they were captured. Osborn sent Widow back to Sharon with an ultimatum: either she would turn herself in, as Osborn had implicated her as Rogers' second shooter, or he would kill Bucky. Bucky was then sent into the custody of the Thunderbolts, who told him that he would be inducted into their group once Rogers was brought back. However, Bucky was secretly freed by Ant-Man and then rescued by Falcon.
After a period of reflection, Barnes decide to give up the Captain America identity in favor of the revived Rogers. Before giving up the Captain America mantle, Bucky and the Black Widow decide to fight and throw the shield one last time. Coincidentally, Rogers was suited up and ready to fight crime that night as well until he witnessed Bucky and the Black Widow depart. Rogers decides to peruse the dynamic duo and upon doing so realized that Bucky would be well off as Captain America. A quick battle ensues when Bucky and the Black Widow encounter Mr. Hyde and his henchman. After the two heroes dispense with the henchman, Mr. Hyde attempts to escape until Rogers joins the battle and defeats him. Quickly after, Rogers officially and respectfully hands the Captain America mantle over to Bucky giving Bucky his blessing.
Wolverine Weapon X
In a distant future, approximately 25 years from Marvel time, a company known as Roxxon begins to send Deathlok cyborgs into the past and assassinate all super heroes in attempt to monopolize the US and possibly the world. Their only opposing force is a group of rebels that just so happens to consist of Wolverine. Their prime directive now is to find and assassinate the rebellion group leader known as the General. After assassinating the Punisher in an unknown time, their next target happens to be the current Captain America, James Buchanan Barnes. It has been hinted that the General is possibly Bucky himself because of his refusal to attempt to save himself possibly distorting the future time line the General has fought so hard for.
When Skadi led her attack on Washington, D.C. Bucky was there to oppose her; however, her power proved too great and he was beat to with-in an inch of his life. Before passing out, Bucky told Black Widow to warn people about the Serpent. Barnes was rushed to Fury, who gave him the Infinity Formula, which saved his life and restored him. Bucky decided to stay underground and has returned to his Winter Soldier identity. Bucky's LMD was buried at the Arlington National Cemetery.