This week marks the 75th anniversary of D-Day, and just like in the movies, the commemoration will try to re-create some of the most famous scenes of that fateful day in June 1944. There will be a mass parachute drop of personnel in vintage uniforms, parades of World War II military vehicles, screenings of film from that time and exhibitions of genuine artifacts such as helmets, guns and other military equipment. As ever, the focus will be on the hundreds of thousands of valiant young men from the United States, Britain and Canada who waded off the landing craft onto the Normandy beaches into a hail of German bullets.

But the heroism displayed on that day, and in the weeks that followed, was not exclusive to the regular forces crossing the English Channel to invade France. Often just as gallant were those already on French soil, who had endured years of a crushing occupation, but who also played their part in securing the Allied victory. Dwight Eisenhower, the supreme Allied commander who planned the D-Day invasion, estimated that the French Resistance, often directed and armed by Allied secret agents, helped to shorten the war by about nine months, not least by blocking German troops from reinforcing their defenses on the Normandy coast.

These French men and women — booksellers, farmers, schoolboys, housewives — show that courage can come from unexpected places. They show us that we can take a stand against oppression or extremism by playing our part, whether large or small, but also that most of us wait to take our lead from others.

Sometimes, the wait is a long one.

Often those who think of the French Resistance imagine some magical force that arose organically and instantly after the country capitulated to the Germans in May 1940. In truth, it took nearly four years — and considerable outside help — for a committed, organized and large-scale force of freedom fighters to emerge. The years of preparation to assist the eventual return of Allied forces proved well worth it, but success was never guaranteed. In the long years of Nazi assault and occupation, resistance was often a lonely and certainly unrewarded vocation.