World War I is often called "the chemists’ war", both for the extensive use of poison gas and the importance of nitrates and advanced high explosives. Poison gas, beginning in 1915 with chlorine from the powerful German dye industry, was used extensively by the Germans and the British ; over the course of the war, scientists on both sides raced to develop more and more potent chemicals and devise countermeasures against the newest enemy gases. Physicists also contributed to the war effort, developing wireless communication technologies and sound-based methods of detecting U-boats, resulting in the first tenuous long-term connections between academic science and the military.