The original version was most often a foe of Captain America while other adversaries include the Punisher, Moon Knight, Ghost Rider, the Runaways, the Liberteens and Deadpool.

Mark Gruenwald created Flag-Smasher as a character in the tradition of the Red Skull: a villain with a symbolic aspect that would make him a nemesis specifically intended for Captain America.

He conducted a one-man terrorist campaign in New York City against nationalist symbols, holding hundreds as hostages until the original Captain America captured him.

For his part, when he confronts the supervillain, Captain America tries to persuade the Flag-Smasher that while his violent methods are unacceptable, his overall goal of world peace and cooperation is laudable and he should promote it by being a positive example, but the fanatic refuses to listen and has to be subdued by force.

[8] He then made a new attempt to create anarchy in the United States through distribution of arms to malcontents, but this time, the Punisher and the Ghost Rider thwarted his plot.

[14][15] Following the original Flag-Smasher's apparent assassination, Canadian ULTIMATUM agent Guy Thierrault assumed the role to continue the spread of anti-nationalism agenda.

[16][17][18] During the Civil War story arc, he attacked the Santa Monica Farmers' Market to show his opposition to the Super-Human Registration Act, but the Runaways defeated him.

[27] A new version of Flag-Smasher and iteration of ULTIMATUM announce their presence to the world by crashing a gala being held in honor of Tom Herald, a conservative senator from Texas.

Attaching time bombs to Herald and six others, Flag-Smasher attempts to coerce two versions of Captain America, Steve Rogers and Sam Wilson, into joining him, before arming both the explosives and "data bombs" that will leak the NSA's surveillance data, decrypt America's nuclear launch codes, and erase the country's electronic banking sanctions and its No Fly List.

The digital bombs and three of the physical ones are disarmed by Rick Jones, but Flag-Smasher and his minions escape after Wilson fails to stop them from shooting Herald.

[32] The group, whose members are empowered by a recreated Super Soldier Serum and possess superhuman strength, seek to restore the world to how it was during the Blip, only to run afoul of Sam Wilson, Bucky Barnes, John Walker, Helmut Zemo, and the Power Broker.