Irregular warfare refers to forms of armed conflict in which military forces do not rely primarily on conventional battles between organized, uniformed armies. In ancient and medieval societies, warfare often combined regular armies with irregular methods such as ambushes, raids, guerrilla attacks, sabotage, deception and the use of difficult terrain. Such methods were particularly important when a weaker political power faced a stronger and better-organized enemy. In ancient societies, irregular warfare was closely connected with geography and local conditions. Mountainous, forested and desert regions provided opportunities for smaller groups to attack larger armies unexpectedly. Ancient Indian political and military thought recognized the importance of unconventional methods. Kautilya’s Arthashastra discusses methods such as espionage, secret operations, deception, surprise attacks and the use of spies to weaken enemies. These practices demonstrate that warfare was not limited to open battlefield confrontation.