Created by Roy Thomas and Frank Robbins, the first Union Jack (James Montgomery Falsworth) first appeared in Invaders #7 (July 1976).

JJ Feild portrayed James Falsworth in the Marvel Cinematic Universe film Captain America: The First Avenger as a member of the Howling Commandoes.

Roy Thomas and Frank Robbins introduced the original Union Jack, James Montgomery Falsworth, as a retired country squire in The Invaders #7-9 (July–October 1976); in the story flashbacks show him in action in World War I as part of Freedom's Five and battling the original Baron Blood, later revealed to be his own brother, while in the present day his brief membership of the Invaders ends when he is invalided saving his daughter, Jacqueline Falsworth, from his vampiric brother.

Thomas and Robbins concluded the plot-line in The Invaders #11 (December 1976); in the story his newly empowered daughter takes his place on the team as Spitfire.

Thomas and Robbins also first featured Lord Falsworth's son and successor Brian in his previous guise as the Destroyer in Invaders #18-19 (July–August 1977); in the story he explains how he received a variation of the super-soldier formula from a fellow inmate while in a Nazi prison.

Thomas and Robbins continued to feature both Falsworths in the series, with the younger becoming a semi-permanent member of the team with issues #23 (December 1977) & #25 (February 1978); in which he joins them on his first mission, while the older appeared in a supporting role in issue #23 (December 1977), in which he helps Dyna-Mite's search for a cure to his size reduction, and #26 (March 1978); in which he introduces Brian to the restored Aubrey in his role as the new Destroyer.

Roger Stern and John Byrne gave Lord Falsworth a contemporary appearance as an elderly country gentleman using a wheelchair for Captain America Vol.

Lord Falsworth appears as a supporting character in Fabian Nicieza and Lewis LaRosa's Citizen V and the V-Battalion: The Everlasting #1 (March 2002); the story begins with a flashback showing him at Brian Falsworth's funeral in 1953 and reveals he assisted the titular fictional secret organization run by his son's lover, Roger Aubrey.

Kyle Higgins, Alec Siegel and Pepe Larraz featured the Brian Falsworth incarnation in the World War II flashback story Crossfire for the 70th Anniversary Issue Captain America #616 (May 2011); in the story Captain America and Union Jack defend a French town under Nazi siege.

Falsworth finally sees the end of Baron Blood with the help of Captain America and the third incarnation of Union Jack (Joey Chapman).

[10] Brian gains the peak of human potential through the help of a dying German scientist who tried to recreate the Super Soldier Formula that resulted in Captain America.

[13] Brian subsequently adopts the Union Jack identity as an adventurer and British government operative in place of his disabled father, joining the Invaders.

[16] Following the war, Brian remains active as Union Jack,[7] and is instrumental in founding the V-Battalion alongside Roger Aubrey, who was revealed to be his lover in the 2002 series Citizen V and the V Battalion,[17] and other heroes of the era.

[volume & issue needed] A car crash on a British road in 1953 abruptly ended Brian Falsworth's career and his life.

[18] Joseph "Joey" Chapman's Union Jack is unique in that he is not a member of the Falsworth line or part of any British aristocratic family.

Chapman later wears an updated, militaristic costume, and joins the New Invaders, led by Jim Hammond, the original Human Torch.

He was a superbly athletic man, but, having been exposed to a variant of the Super Soldier Formula, was enhanced to the peak of human potential, and was highly trained in armed and unarmed combat.

This version is one of several POW's who were held at a HYDRA factory before they are liberated by Captain America and subsequently join his Howling Commandos.