As an army commander, during the Seven Years' War, he emerged as one of Frederick's most capable generals. In the Battle of Lobositz, his regiment suffered heavy losses, but Frederick II praised Hülsen for his bravery: indeed, at least one historian attributed Hülsen's success at Kolin to his hard-headed fighting. Hülsen, "not much troubled with either imagination or intelligence, was as brave a battle captain as his [Frederick's] army possessed." Hülsen commanded the leading element of Frederick's task force, while his named regiment was fighting under Lieutenant General Joachim Christian von Tresckow. His mission at Kolin was to march along a high road paralleling the Austrian front; after he reached the village of Křečhoř, he was to shift right, clear the heights behind the village and take position facing west, against what Frederick presumed would be the exposed Austrian flank. The complexity of the battle orders, and the conditions of terrain made the execution of Frederick's wishes difficult; Hülsen's troops did not actually advance until mid-afternoon. With these troops, and further support, he managed to take a decisive step in the late afternoon and defend the line until the night. In his writings on the history of the war, Frederick II expressly praised Hülsen's zeal in this battle: certainly, Hülsen's deliberate advance in the afternoon and his stubborn defense of his position into the late afternoon made it possible for him to cover the Prussian retreat; this, as much as Frederick's paucity of generals, warranted Hülsen's promotion to lieutenant general on 6 March 1758.