How did new technology change the way war was fought?

Throughout history technological developments have changed the way war has been fought.

Cannon made the large defensive castles of the middle ages obsolete.

Firearms made the suits of armor worn by medieval knights worthless.

Aircraft allowed nations to fight in the sky as well as on the ground, and bomb their enemies far behind any front line on the ground.

Small, portable anti-aircraft systems lead to stealth technology, and also changed how bombing campaigns were carried out, and have even lead to the use of weapon equipped drones.