The GL (Gwardia Ludowa - People's Guard) was founded by the PPR (Polska Partia Robotnicza - Polish Workers' Party) in early January of 1942 as a left-wing military conspiratorial organization whose aim was to bring about the liberation of Poland from the German occupation. The name GL was not officially adopted until March. The GL was open to all, regardless of their ethnic backgrounds and political convictions, and all PPR members were required to join the GL by default; however, membership in both the GL as well as the PPR was purely voluntary. A number of small left-wing resistance organizations, some in existence since at least 1940, were absorbed by the GL. Its activities were directed by the Central Committee of the PPR, via a three-member secretariat, made up of the committee's secretary, one more committee member, and the chief of staff of the GL.

During 1942-1943 the GL units conducted about 1 600 armed actions, including 410 directed against the enemy railway transportation (194 trains were derailed) in addition to 131 against the railway stations, tracks, and bridges, as well as 404 against the German police forces (including over 270 against the posts of the police and gendarmerie); fought 117 engagements and clashes against the German pacificational units, conducted 16 attacks on "Germans only" locales; in the struggle against the oppressive German administration and economic exploitation it carried-out 664 armed actions, as a result of which around 200 German government offices were demolished, in 28 actions various towns were captured - during the course of which many prisoners were freed from the local jails - in 85 actions it recovered confiscated foodstuffs - mostly returning them to the plundered Polish population - in excess 90 actions industrial installations were attacked destroying/disrupting their production capacity, in hundreds of instances German policemen, troops, and others were dis-armed.

Proportionally to its small numbers (~5 000 members by the end of 1942, and roughly twice as many by the end of the following year), and despite its "lateness" in entry on the resistance scene, hostile attitude towards it by some of the other underground organizations, the GL made a significant contribution to the Polish resistance efforts, often leading the way in the field of the armed resistance ahead of much more numerous and older organizations.

On the 1st of January, 1944, the GL was transformed into the AL (Armia Ludowa - People's Army). GL was one of the co-founding organizations of the KRN (Krajowa Rada Narodowa - National Council of the Country).