There was no movement in the overall standings as Alberto Bettiol (XDS Astana) took the stage win from the break.
Filippo Ganna was keen to make the break, but was denied on multiple occasions by an aggressive peloton that wanted to deny the Italian victory in his hometown.
Once the escapees had a sufficient gap, the peloton eased and allowed their advantage to grow, with Thymen Arensman, Egan Bernal and other GC riders keen to preserve energy ahead of stage 14’s mountain test.
Earlier, Filippo Ganna and Connor Swift had been active in trying to get into the breakaway - which would seem pivotal due to the flat nature of the stage,
However, Ganna was a marked man and his multiple efforts to escape were denied by the bunch behind.
A break finally went clear after around 45 minutes of cat and mouse chasing, which then saw the peloton reduce the pace ahead of a key weekend.
Arensman and Bernal finished in a reduced bunch which finished over 13 minutes behind winner Bettiol, with attention already switched to stage 14's GC test.
Shmidt fourth on Dunkerque cobbles
Artem Shmidt battled to finish fourth after his counter-break succeeded on stage three of 4 Jours de Dunkerque.
Shmidt and Lucas Hamilton were part of a strong group that moved clear of the bunch on the cobbled finishing circuit of Wallers Arenberg.
The peloton threatened to catch them on multiple occasions, but the group were able to evade capture and accelerated on the final cobbled sector to ensure they would contest the stage win between them
Rasmus Tiller (Uno-X Mobility) stole a march on the group however, with nobody able to catch him, with Shmidt finishing fourth in the chase group to move up to sixth overall.