During World War I, Lord Falsworth was recruited by the British army to become one of the first public superhero champions: Union Jack. His superiors decided to create a guise that would strike terror in enemy hearts as well as rally troops-- by having Falsworth appear as a personification of the British national flag. He fought valiantly throughout the war, eventually joining similar national heroes in a group called Freedom's Five. He also fought the vampire Baron Blood, a German agent, and the infamous Hellfire Club, which he prevented from awakening a harbinger of Apocalypse, Ch’Vayre. After the war was over, Union Jack was retired, and Falsworth settled back into life at Falsworth Manor and began to raise his family.

During World War II, Baron Blood returned to the countryside near Falsworth Manor to begin a new reign of terror. Montgomery's daughter, Jacqueline, was attacked by the vampire, but saved by the original Human Torch, who drove it off. Jacqueline invited the Torch and his team, the Invaders, to dinner at the manor, where Falsworth then revealed to family and company that there was one other super-hero in their midst — himself! He told of his career during World War I as Union Jack and volunteered the use of his mansion as a base of operations for the Invaders. He was even inspired to don the Union Jack identity to fight alongside the Invaders against Baron Blood. During the battle, Falsworth finally discovered the identity of the vampire was his brother, John, only to have his brother crush his legs under a boulder. He managed to pry to boulder off, which subsequently knocked Baron Blood onto a stalagmite, impaling him. Although paralyzed from the waist down, he did accompany the Invaders on a mission into Germany, where he met and reconciled with his son Brian, who he had thought fled to German as a Nazi sympathizer. He offered his son the mantle of Union Jack, passing on the legacy.

Years later, Falsworth outlived his son, who died in a car accident. Growing ill with age, his daughter came to live at Falsworth Manor to help assist him. At this time, Falsworth read about a series of murders, strongly believing that a revived Baron Blood was behind them. He contacted Captain America for help and devised a plan where Falsworth would don the Union Jack garb to draw the vampire out. Unfortunately, Falsworth suffered a heart attack before the confrontation, and his place in the trap was taken by his grandson's friend Joe Chapman; Chapman and Captain America together defeated the vampire. The heroes committed Baron Blood’s body to a funeral pyre, at which time Falsworth quietly passed away, knowing his brother’s evil had been laid to rest.