Do you mean, what invention utilised during the Civil War changed combat?
The rifle-barrelled cannon. Or the minie-ball.
The post-war invention would have been the machine-gun.
The invention of gunpowder in 9th century China significantly changed warfare. Initially developed for use in fireworks, it quickly transitioned to military applications, leading to the creation of explosive weapons, cannons, and firearms. This innovation revolutionized combat tactics and strategies, allowing for greater destructive power and altering the dynamics of battles both in China and eventually around the world. Gunpowder's impact extended beyond the battlefield, influencing the development of modern warfare.
The machine gun changed warfare
How about this? "The Civil War was the birthplace of technologies that changed the nature of warfare forever."
sucking balls
ANSWER The building of the Ironclads.
Gunpowder
Iron Bridge
Aerial vehicles
gunpowder and the abacus.
World War 2 changed the world forever by teaching us a lesson in the areas of atomic warfare, and the treatment of war prisoners.
The machine gun changed warfare
How about this? "The Civil War was the birthplace of technologies that changed the nature of warfare forever."
The invention of the Firearm
zeus-- > Athena is a Goddess .
sucking balls
The invention of machine guns, gas warfare and trench warfare
If by "solution for trench warfare", you mean a way to end trench warfare, then the invention and widescale use of tanks, bombers and the Blitzkrieg in WWII solved trench warfare.