Due to his disability, Crescent was exempt from military duties, but joined the Alliance network [fr] in the French Resistance by February 1941.

He completed missions in Germany, on behalf of the special services [fr] in September 1944 until June 1945, seconded to the Third United States Army.

[8][9] In 1970, he brought about the formation of PSG, with the help of some passionate industrialists like him (Henri Patrelle and Pierre-Étienne Guyot), and in conjunction with the French Football Federation.

The professional team was created, taking care of its young players, and participating in the national championship to support the new stadium, the Parc des Princes, replacing the previous one that had to be destroyed for the penetration of the Boulevard Périphérique.

[12][13] For the occasion of the 50th anniversary of PSG in 2020, the president of the club Nasser Al-Khelaifi along with the city of Poissy decided to pay tribute to Crescent by renaming a street near the new Paris Saint-Germain Training Center in honour of him.

[14][15] His entire life, Guy Crescent helped people with disabilities,[16][17] and was involved in numerous associative and humanitarian actions, particularly in the fight against cancer and the reintegration of former drug addicts into the working world.

Crescent would bring his full support to the Association des Paralysés de France [fr], for the development of applications and jobs in companies for people with polio.

In the same year of 1952, he participated at the Raymond Poincaré University Hospital (pavillon Letulle), taking care of paraplegics assigned there by Professor Jean Benassy.