Another advance affected warfare: the semaphore system had allowed the French War-Minister, Carnot, to communicate with French forces on the frontiers throughout the 1790s. The French continued to use this system throughout the Napoleonic wars. Additionally, aerial surveillance came into use for the first time when the French used a hot-air balloon to survey Coalition positions before the Battle of Fleurus, on 26 June 1794. Advances in ordnance and rocketry also occurred in the course of the conflict.