For decades the First Line defended the world from threats both home-grown and alien. The group formed in 1958 when Yankee Clipper, Liberty Girl, and Black Fox were brought together by Agent Scott of the NSA to investigate security breaches at a Long Island research center, where scientists were secretly studying a downed UFO. There the heroes encountered both the Monster Hunters and a couple of super-villains hired by Zuhn, the Skrull whose ship was being examined. Ironically Agent Scott was really Velmax, Zuhn's shipmate, though neither alien recognized the other. Zuhn shot Velmax with a bio-moleculizer, causing him to lose control of his form, but the heroes assumed he had been mutated. Velmax became the metamorph Effigy, joining with Nightingale, a healer, and the three heroes he had gathered to form the First Line at the Clipper's suggestion.
Over the years the group gained and lost members, and fought threats such as the Red Front, the Yellow Claw, the amnesiac Sub-Mariner, the Nazi Rumor, the mind-controlled Venus, the lunatic therianthrope Howler, the criminal Typhoon, Axis, the Scythe, the vampiric Nocturne, Kang, Warlord Kro and the Deviants, Blackjack and Positron; the latter two later reformed and joined the Line themselves. Among their allies were Hipster (later Captain Hip), Sunshine, Thor, Nick Fury and Dr. Strange, and several of their adventures were covertly witnessed by 22nd century time-traveler Cassandra Locke.
The team faced both triumphs and tragedies. In November 1963 Liberty Girl was slain by Chimera (Zuhn in a new identity), and Yankee Clipper was lost to them, sent hurtling decades into the future. In 1969 they stopped a Skrull plan to destroy the Apollo 11 mission to land on the Moon; Mr. Justice placed evidence there proving Skrull plots which would thwart the shape-shifters again in Locke's era. Around 1973 the group disbanded rather than let Nixon use them to suppress Watergate, and Effigy became reporter Bob Woodward's "Deep Throat."
A new incarnation of the team formed in the early 1980's to rescue Mr. Justice, who had been shot down over Halwan, but their mission proved to be a decoy; Blackjack was killed, and Black Fox quit in disgust. Effigy, however, decided to keep the Line together as a loose-knit grouping lasting several years. Another member, the Inhuman Yeti, lost control in an unspecified conflict involving Rapunzel, after which he exiled himself in shame; Yeti was later seduced by a Skrull spy, Korya, who turned him into a sympathizer in their subsequent invasion of Earth. Another Skrull spy, Zankor, was captured and revealed the imminent massive fleet on its way.
The First Line assembled many of Earth's superhumans and met the incoming warships above the surface of the Moon. Most of these champions died, but Effigy and Pixie managed to set off a chain reaction which blew up the armada. Yeti made it to an escape pod prior to the end, and Pixie and Makkari both survived the explosions to eventually be reunited with Yankee Clipper. The First Line, however, was finished; Earth was saved, but it had lost an entire generation of heroes.