Early medieval artillery consisted of weapons such as the catapult, trebuchet, and ballista; they were ideal for siege warfare. The widespread use of gunpowder in the 14th century led to cannons being adopted by many armies and decreased the importance of fortified structures such as castles. During the Napoleonic Wars of the early 19th century, Napoleon, a former artillery officer, perfected artillery tactics to great effect using massed artillery batteries to fire upon critical points of enemy lines, before infantry and cavalry assaults were unleashed. The technology continued to be improved and adapted with artillery serving many different roles in the 20th and 21st centuries, from long-range fire support, short-range fire support with weapons like the mortar, being used as anti-tank guns, and also for firing upon aircraft.