The German was the fastest member of a 10 man group that broke clear in the final kilometres and had the necessary speed to blow away the opposition.
Thomas Vockler (Team Europcar) was the first to attack for the line but faded and could only finish fourth with Danilo Napolitano (Acqua & Sapone) and Pierrick Fedrigo (FDJ-BigMat) finishing second and third.
Thanks to time bonuses Degenkolb takes the leaders jersey with a four second lead over Napolitano.
Five riders were clocked on the same time at the front with another group of five three seconds further back.
A group of a dozen or so finished 13 seconds off the leaders with the two biggest groups of riders then 16 and 38 seconds behind come the finish.
Despite being called the Quatre Jours de Dunkerque the race actually takes place over five days.
Stage two sees the riders travel 180.2km from Berck sur Mer to Montreuil sur Mer.