The concept of "total war" — war that mobilizes entire societies rather than just armies — is usually dated to the French Revolutionary Wars.
Before Napoleon, European warfare was limited by convention, logistics, and the expense of professional armies. Armies avoided unnecessary battles; the goal was often to maneuver the enemy into an untenable position.
The levée en masse (1793) changed this: France conscripted its entire male population, giving it armies of unprecedented size. The other powers had to follow or be overwhelmed.
Total war didn't just change tactics; it changed the relationship between states and populations. War became everyone's war.
Related: logistics-wins-wars, fog-of-war-clausewitz