What new technological advancements came out of World War 1

Tanks. In 1914, the “war of movement” expected by most European generals settled down into an unexpected, and seemingly unwinnable, war of trenches, Flamethrowers,  Poison Gas, Tracer Bullets, Gear Air traffic control, Depth Charges, and  Hydrophones.

Explanation: Machine gun - The machine gun was improved during the war. It was made much lighter and easier to move around. Flame throwers - Flame throwers were used by the German Army on the western front in order to force the enemy out of their trenches. Chemical weapons - World War I also introduced chemical weapons to warfare. Hope this helps!

couples could only have one child to reduce the population growth.