How did poison gas change the nature of war?

When were National Identity cards issued before the war? What is the official logo of USMC? What did liberty cabbage mean during World War 1? How long does nerve gas last in the air? What were the roles of American women during the Vietnam war? Why was the Battle of Bull Run a surprise? To help pay for the world war 2 the US government relied heavily on the what? What the history and value of a 1914 coin with a woman with 13 stars around the coin an a V on the back surrounded by a wreath? How long did soldiers sleep for in WW1? Who did hull support in the civil war? What were those metal obstructions on the beaches at Normandy and what were they for? What was General Sherman's order 15? What Battle had the most men killed? Was there a black legion hate group in the 1930's? What are the names of the military ships sunk un world war 2? What war was between the thirteen colonies and British mercantilism? What was it like to be a spartan soldier? What was the name of the other hill in the Battle of Bunker Hill? What are the symbols for d day? What nation controlled most of the little tray that was allowed?