First Appearance: Giant-Size Invaders #1 (June 1975).
Appearances: Giant-Size Invaders #1, Invaders v1 #1-41, Invaders v2 #1-4, Invaders Annual #1, Marvel Universe #1-3, Marvel Premiere #29-30, Fantastic Four Annual #1, Marvel Two-in-One #20, What If? v1 #4
Years Active: 1941-1945.
In 1941 the German superman Master Man was a threat to the British and to Winston Churchill in particular. Bucky (I), Captain America (I), Human Torch (I), Namor the Sub-Mariner, and Toro came together to defeat Master Man. After the five did so Churchill persuaded them to stick together and operate as a team against the German threat. They did, and fought various Nazi menaces. After having been brainwashed and then freed by Bucky (I), the Invaders teamed up wih the Liberty Legion to fight the Red Skull.
While fighting the German vampire Baron Blood the Invaders welcomed Union Jack (I) into their ranks. His legs were crushed during the battle, however, and he was forced to retire. His daughter Jacqueline, aka Spitfire, replaced him as an Invader. Following her inclusion the Invaders fought other villains and teamed up with the Crusaders and the Destroyer, who joined the Invaders as Union Jack (II).
Later the Invaders fought against the Scarlet Scarab. During a battle with the German superhuman Agent Axis Bucky (I) and Toro met Golden Girl (II) and the Human Top (II), and the quartet formed the Kid Commandos. Then the Invaders, the Whizzer, and the Liberty Legion joined together to fight the Iron Cross; after this battle the Whizzer and Miss America joined the Invaders.
Some time later, during a battle with the Battle Axis, the Invaders were joined by the Blazing Skull and the Silver Scorpion, neither of whom were ever made official membes but both of whom were made honorary Invaders, like the Liberty Legion.
With the end of the war the Invaders disbanded and reformed as the All-Winners Squad.
Useful Invaders Site
The Invaders. Eric Colley's site, which unfortunately hasn't been updated in two years. But it still has a good mix of information and graphics.