Complex sentence: The balloon found its first use in the, where in the Battle of Fleurus the gathered information and the demoralizing effect on the Austrian troops ensured victory for the French troops.
Split into simpler sentences: The balloon found its first use in the, where in the Battle of Fleurus they gathered information. Moreover, the presence of the balloon had a demoralizing effect on the Austrian troops which improved the likelihood of victory for the French troops.