- In your warped, twisted mind, you think of combat as a game... some sort of noble sport! Well, it's not! It's a grim, dirty business... but it's a business that no one knows better than I do!
- -- Captain America
Steve Rogers grew up in Brooklyn during the Great Depression, a scrawny kid protected from neighborhood bullies by his best friend James "Bucky" Barnes. Horrified by newsreel footage of the Nazis in Europe, Rogers was inspired to enlist in the Army around the time the United States entered World War II, but because time and again he failed the physical tests, he was rejected. His luck changed during another visit to Recruitment Center when Military Sergeant Dugan recruited him for Project: Rebirth after hearing Rogers's pleas. After voluntarily subjecting to surgery, steroid treatments, and other experimental treatments supervised by Dr. Erskine, Rogers became the first genetically-enhanced super-soldier. During the final treatment however, he noticed a suspicious soldier focusing on him instead of standing guard. The shady man revealed himself as a Nazi spy sent to murder Rogers in the event that he survived the experiment. Rogers stopped him, but not before the spy murdered Doctor Eskine and a few American soldiers who attempted to stop him. Fully committing himself to the American war efforts, Rogers bid farewell to his sweetheart Gail and became Captain America.
For the next three years, he undertook numerous covert operations, often accompanied by Bucky, now a war photographer, and sometimes "Lucky" Jim Howlett (later the X-Men's Wolverine). During World War II he came into battle with the alien Chitauri Herr Kleiser, who introduced a prototype A-Bomb made with alien technology and meant to target the White House. Though too late to stop the bomb's launch, Captain America managed to get to the bomb moments before its launch. In a successful attempt to stop it in mid-air, he fell to the sea, presumed deceased. However, through a combination of his super soldier physiology and the arctic cold, Captain American went into a cryogenic state for over fifty years.
Revival and joining the Ultimates
Decades later, the body of Captain America was found in the Arctic Ocean, frozen in a block of ice. When scientists analyzed him, it was as if he had not aged a day; it is yet to be known whether cryogenic preservation or the super soldier serum prevented aging. Once awakened, he thought the assigned S.H.I.E.L.D. agents were a group of Nazi soldiers who had captured him, but eventually realized that he was in a different time after seeing modern New York City. He found out his best friend, Bucky Barnes, had married to his fiance and that all his loved ones were dead.
After catching up to his new era, the Ultimates were faced with the Hulk. Rogers was able to put down the Hulk briefly in combat. When he was about to inject the Hulk with the antidote, Hulk made a surprise attack and broke the needle and Hulk then began beating Cap, until Thor came to the rescue. After Hulk had reverted back to Banner, Cap knocked him out and had him taken back to the Triskelion.
After learning his teammates Hank and Janet Pym's domestic quarrel's had left Janet hospitalized and nearly dead, Rogers tracked the now-fugitive Hank Pym to a bar and engaged him in combat, emerging victorious. He brought Janet flowers and other gifts afterward, but she was not amused by his actions and rejected his gifts. Rogers soon discovered that his nemesis, Herr Kleiser, had survived World War II due to his alien abilities. Cap had previously stated that he had killed Kleiser "twice." When Kleiser resurfaced, Captain America and Kleiser resumed their rivalry.
During the Chitauri invasion, Rogers fought Kleiser in combat, but was unable to defeat him due to his regenerating capabilities. When the Hulk was dropped into their battle, he convinced Hulk that Kleiser was "hitting on Betty", causing Hulk to mutilate and eat Herr Kleiser, ending Kleiser once and for all. After the successful battle against the Chitauri, Rogers danced with Janet Pym and a relationship between them bloomed, though the relationship soon became sour as Roger's 1940s personality created a generation gap between them and leading the Wasp to secretly return to her ex-husband.
During the Ultimate War, the Ultimates battled with the X-Men after Magneto was found alive. Cap was then reunited with "Lucky Jim" Howlett, presently known as Wolverine. During the battle, Captain America called Wolverine by his given name, causing Wolverine to become disoriented. Cap then fired a machine gun into Wolverine, rendering him unconscious.
Norman Osborn's "Six":
During the Ultimate Six event Captain America led the Ultimates in the arrests of Electroand Kraven the Hunter. Later those two – along with the Sandman, Doc Octopus, and Norman Osborn / Green Goblin — escape from S.H.I.E.L.D. Cap becomes very disheartened when he finds out that these villains were all a result of trying to duplicate the Super Soldier serum. During an attack on the White House lawn Captain America wrestled with Spider-Man, neither overpowering the other. Cap then explained to Spider-Man that his aunt was safe with S.H.I.E.L.D. Captain America then fought the Green Goblin, landing several hits while not being hit once.
Betrayal and Liberators Invasion
Cap and the Ultimates were later under fire from the press and public due to the belief that Thor had revealed that Bruce Banner was indeed the Hulk. In a meeting with Thor, Thor brought up the fact that Captain America killed many people and still goes to church, saying that he's confused with his morals. The Ultimates fought Thor and eventually captured him when his power belt was removed by Quicksilver. From then on the Ultimates became more involved in foreign affairs, with America attempting to control natural resources from Third World countries.
The Ultimates' actions ultimately led to several nations secretly forming their own superhuman team, dubbed "the Liberators". Captain America was framed by Black Widow for the assassination of Hawkeye's family and was hastily subdued and arrested while visiting Bucky for consolation after the bitter ending of his relationship with Janet Pym. He was imprisoned in the Triskelion.
When the Liberators attacked, he was freed by the Wasp and defeated the Schizoid Man while escaping. He and the Wasp soon reached the White House where they met with Hawkeye, Nick Fury, the Scarlet Witch and Quicksilver. Captain dueled with his Liberators counterpart, the Colonel and emerged victorious after stabbing the Colonel in the chest with one end of the double-bladed energy sword that the Colonel used.
After the Liberators were defeated, Steven Rogers somberly watched the Colonel's body being removed by S.H.I.E.L.D. and remembered his words about America's current role in the world. Seeing that the Ultimates role in "policing" the world for the US Government would lead to more Liberators-style outcomes, Rogers and his team decided to leave S.H.I.E.L.D. and work as an independent team.
Black Panther & The Savage Lands
Before the events of the Liberators' attack, Steven befriended T'Challa, the Black Panther, and trained him in for membership in the Ultimates. As the team's deputy leader, Rogers was uncomfortable with the notion of working with a man about whom he knew so little. After Steve discovered that T'Challa's throat was heavily damaged, causing muteness, he pressed Fury for more information. Fury lied about the origin of T'Challa's scars, and about T'Challa's history with the Weapon X Program, while also stating that everything about the "Black Panther" was classified.
Captain America eventually established a communication with T'Challa and learned of the man's desire to return to Wakanda to see his father. Since no one but Cap had ever seen T'Challa's true face, Steven then adopted the role of the Black Panther in the Ultimates, enabling the real Black Panther the chance to return home.
Following the Ultimates' severance with S.H.I.E.L.D., Rogers secretly adopted the identity of the Black Panther from his teammates as he was overburden with being unworthy for the title "Captain America" given the Liberators' invasion and how the public would view him. Eventually his secret was revealed when Juggernaut literally beat Rogers's costume off of him.
Captain America drowned when Magneto's Ultimatum Wave hit New York. While in Valhalla, Thor appeared to save the life of his love, Valkyrie and traded his own life for those of Valkyrie and Steve Rogers. Cap then lead a team of Ultimates and X-Men against Magneto and vowed to not let Thor's sacrifice be in vain.
Father of Red Skull & Evading the Avengers
Months after Ultimatum, Captain America and Hawkeye fought a group of AIM terrorists at the Baxter Building who were stealing the building's valuable and powerful technologies. After defeating a majority of the terrorists, Cap encountered the Red Skull, who easily beat him. The Red Skull then shockingly revealed to Steven that he was his own son before throwing him out of a helicopter. Cap was saved by Hawkeye.
After learning that the Red Skull was indeed his son by Gail Richards, Captain America decided to personally confront his son. He abandoned the Ultimates and attacked S.H.I.E.L.D. agents in the process. Rogers later infiltrated the Army's computer database and discovered the truth about the Red Skull. Sometime later Captain America was in Paris, France for his own reasons. Rogers created a plot to placed tracers on Nick Fury's Avengers, who were coming to capture him. Following the tracers would allow him to later find his son, who the Avengers were also chasing. After a brief fight, Cap managed to place tracers on War Machine, Red Wasp, and Black Widow. Cap was subsequently subdued and captured by the Avengers.
Escaping the French S.H.I.E.L.D. guards, Cap jumped into a tele-plane (a jet which teleports), and teleported to Alaska, where the Avengers were fighting the Red Skull. When he arrived, Red Skull, who was wielding the Cosmic Cube, subdued Rogers's jet. However, Cap gave Hawkeye the coordinates for the Red Skull's position, and he fatally impaled his son on the teleplane's nose. After the Red Skull was in custody, Rogers emotionally bore witness as Gail Richards reunited with her dying son.
The Defenders' Theft & Loki's Revenge
Steve Rogers is currently a member of the new version of the Ultimates, aptly named the New Ultimates. Steve helped Valkyrie, Zarda, Iron Man and Hawkeye fight off an attack from the Defenders, but they managed to steal Thor's Hammer before they retreated.
Later he confronted Valkyrie about her involvement with the Defenders and threatened to kick her off the team if she did not talk. Later, when Valkyrie is under the Enchantress's power, he fights Valkyrie, where she destroys his shield.
When Thor is revived, Rogers tries to reason with him, but in his rage, Thor attacks the Ultimates and Loki's forces. After Valkyrie calms Thor down and convinces him to protect the Earth again, Thor gives Steve a new shield made in Asgard.
Frank Simpson & New Super Soldiers
S.H.I.E.L.D. and MI-6 made an agreement for a joint infiltration mission in North Korea. The North Korean government had contracted a mercenary that was attempting to mass-produce super soldiers like Captain America. Because of the sensitivity of western nations entering the country, it was intended to be a black-ops mission to avoid being identified, but to the British team's dismay, Rogers disobeyed instructions (he was unwilling to hide his identity) and appeared in his usual gear, clearly identifying himself.
During the mission, they went to investigate and confirm the progress of the enemy's super soldier development, but found Jung (North Korea's super soldier) dying and burning. As the MI6 agents tried to salvage the mission, Cap gave chase to the mercenary and, to his surprise, he was out-matched. He would find out his opponent is Frank Simpson, Vietnam's super-soldier.
The Death of Spider-Man and Ultimate Fallout
Are you kidding? You took a bullet without even hesitating. When you grow up, you're going to be the best out of all of us.
With Peter Parker chosen for Ultimates' training, it would come as a shock to the young web-slinger when Steve came down on him, telling Spider-Man that he was not ready to be a hero and that he did not deserve to wear the costume. Instead, Peter proved him wrong, taking a bullet meant for Steve, and stopping the Sinister Six from killing his friends and family. Grief-stricken, Steven finally confronted Aunt May at his funeral and told her about what happened. In anger, Aunt May slapped Steve and left the funeral. 
Unable to cope with events, Steve quit being Captain America. After the attack on Asgard by the Children of Tomorrow, Nick Fury tried but failed to convince Steve to retake his role as Captain America.
Divided We Fall
Steve moved to Alaska, but after watching the invasion and purges of the Nimord Sentinels on TV to most of the United States, he decided to return to action and rejoined the Ultimates. He and his team helped the return of Texas as a state of the USA and continue to fight hostile forces across the world. With the popularity of President Howard decreasing, elections were opened. After he saved dozens of innocent lives from the attack of robotic Wasps before the eyes of the cameras, Carol Danvers informed Rogers that he had won the national elections and he would become the next President of the United States.  He accpeted, and among his first actions he stopped a war between North and South Carolina, and dismissed Agent Flumm as the director of S.H.I.E.L.D., giving that position to the Black Widow.
Captain America led the Ultimates during the battle for Wyoming against Hydra and Modi in which the heroes were triumphant and managed to reunite the shattered country. After preventing a nuclear disaster derived from a plot made by Ford (the special advisor to California's governor) to incriminate the United States of attacking California, Rogers resigned from his charge as president.
Steve was present during a meeting in which Invisible Woman informed S.H.I.E.L.D. about the Infinity Gems she had been gathering along Thor, and the moment in which the mysterious Kang freed both Hulk and Reed Richards from the Triskelion, stole the Gems and formed along them and Quicksilver the Dark Ultimates. The Ultimates barely escaped, but Captain America decided to be left behind in order to stop the villains, although he was defeated.
Captain America was imprisoned in the Negative Zone, and Hawkeye and Thor soon joined him. But all three of them were rescued by Iron Man, whose consciousness survived electronically after Reed Richards left him to die in order to retrieve one of the gems fron Tony's brain, as he managed to hack a H.E.R.B.I.E. Tron in order to use it to free the captive Ultimates from the Negative Zone.
The Ultimates finally confronted an out-numbered Reed along with the Howling Commandos, but the Maker's cavalry arrived in the form of Kang wielding the final gem, who also revealed herself as being the Sue Storm from a near future.
During a furious battle against Reed Richards and his Ultimates, Steve managed to help Stark acquire the Infinity Gems and depower the Maker. When he was about to face Richards, an immense flux of energy echoed through time and space and the Gems were destroyed. Kang stated that what she tried to prevent just happened, and she left stating she would try to go back further in time.
Unknown to them, the flux of energy had brought a powerful being known as Galactus from another universe to this one, and it started approaching Earth.
After Galactus destroyed New Jersey, the Ultimates started working in finding a way to defeat him. After accidentally revealing themselves to Galactus, the cosmic being started approaching the Triskelion. To give S.H.I.E.L.D. the time necessary to move away, Steve used a jet to fly near Galactus and distract him. Captain America directed the jet towards Galactus' face and was last seen abandoning it before it crashed. It is clear that he did not survive the fall. The entire country mourned his death.