During the Thirty Years' War, Kaarst was attacked several times by hostile armies, e.g. the one of Northern-Hesse (Northern-Hesse collaborated with Sweden and France, whereas the southern part of Hesse did not). Some time in 1642, a Hessian troop entered the city murdering the local preacher and destroying the vicarage. From 1794 till 1814 Kaarst was in the area occupied by France under Napoleon I. The French redrew district boundaries in 1798 and assigned Kaarst to Kanton Neuss. A relic of Napoleon I is the Nordkanal, a canal to connect the rivers Maas and Rhine.