Why didn't the Nazi's use Chemical Warfare like they did in WW1?

Question:

Why didn't the Nazi's use Chemical Warfare like they did in WW1?

Why did the nazis use their chemicals in WW2?
They were using em in gas chambers.
Sense the nazis violated every warfare law, then why didn;t they use chem. anyways?

Best Answer - Chosen by Asker: You need stationary targets like trenches for gas warfare, which meant that the moving fronts of WWII were the worst place to use them. They also had plenty of veterans who remembered the gas of WWI and the backlash against that use would have been very violent. At 89 my neighbour still reacted with horror when telling me how he watched his friends cough up their lungs, the Germans did the same.
Besides, it was against the war rules and a good part of the Werhmacht and their officers still held to those rules.