Answer:
Three new weapons first used in WW1 were Tanks, Gas, and portable machine guns
Explanation:
TANKS - Tanks allowed for allied soldiers to cross the barren wasteland of no-mans-land, which effectively allowed for the war to end sooner. Tanks also shaped the whole of world war 2
GAS - Gas made people question what was human about war, and were did it go too far. Gas also gave the axis a advantage over the allies, and set a massive anti-gas production into affect (like making gas masks)
portable MACHINE GUNS - this invention has shaped war as we know it. The ability to kill multiple people in one clip increased the number of people killed in the war.
hope this helps :)
