The earliest maquis groups, emerging in 1942, were ideologically driven resisters, escaped French soldiers and others fleeing persecution at the hands of Vichy and the Gestapo (including some French priests). Despite making up less than 1% of the French population, 15-20% maquisards were Jewish, and the maquis also included thousands of Spaniards who fled to France with the ascendency of Franco, many of them experienced antifascists who guided greener recruits.
Maquis membership boomed after the hated forced labour drives of 1942 and 1943, which triggered strikes, demonstrations, subversions and riots. Fleeing the draft, by autumn 1943, 15,000-20,000 had joined or formed maquis units in the French countryside. The last labour push in mid-1944 recorded a noncompliance rate of 95%.
These disorganised groups, living rough in Brittany and southern France, assumed a romantic, outlaw status for many rebellious French youths. Ian Wellsted of the SAS, arriving in the Morvan region, described meeting a maquis unit:
"It was hard to tell what they had been before the German labour laws threw them all together in the depths of the wild woods. Some had been shopkeepers, artisans, young sons of wealthy parents. Others were scum of the gutter and many were soldiers. Now, however, all were much the same."
Supported by the SOE with airdrops, the Free French regarded these unpredictable units with suspicion. However, it was precisely this unpredictability that made them difficult for Vichy and the Gestapo to track, as they harassed Milice and German troops, conducted raids, intimidated collaborators, helped rescue Allied personnel and conducted acts of sabotage. Through a coordinated sabotage campaign, these units would play an important role in D-Day.