Chemical weapons were not used in any significant capacity during World War 2, the only times I can think of when they were thought of or mentioned was when an US supply ship was hit by the Luftwaffe sitting in a port in Italy, that was carrying chemical shells, by accident. In the Pacific the US military was considering using chemical weapons to get the Japanese out of Iwo Jima or Okinawa, where they were very well dug in cave networks.

How about land mines?

Mines were extremely prevalent, hell there still digging them up in Russia I'd imagine., during the Battle of Kursk, the Russian laid over 1 MILLION land mines, alone.