Final answer:
During WWI, the Germans launched the Kaiserschlacht in March 1918, and in WWII, they initiated the Battle of the Bulge in December 1944 as their last major offense in the West.
Step-by-step explanation:
The Germans launched a major attack along the western front during World War I with the Kaiserschlacht, or Spring Offensive, in March 1918. This offensive was a series of five major attacks aimed at breaking through the Allied lines before the Americans could fully join the war. Despite initial successes, by the middle of July 1918, each offensive had failed to decisively defeat the Allies. In World War II, the Germans launched another significant western offensive with the invasion of Norway and Denmark on April 9, 1940, and a more extensive attack through the Low Countries and France starting on May 10, 1940. By December of the same year, in an effort to counter Allied advances, Germany initiated the Battle of the Bulge, the last major German counteroffensive in the West.