The tank was born on the battlefields of WWI where it had to combat not only enemy fortifications, but also mud. Tanks were often lost not from enemy fire, but from being stuck on cross country terrain. Engineers and the military first started thinking about how to improve mobility of their vehicles. Further improvements focused on improving mobility in general, but advanced methods of driving on soft terrain did not progress past experiments. Engineers returned to the issue of improving off-road mobility in WWII. In addition to mud, tanks got a new enemy: snow. This issue was most prevalent on the Soviet-German front where there was more snow than anywhere else for obvious reasons.
The first attempt to make an improvement to tank mobility was made in 1917. It quickly became clear that tracks used on British tanks have poor traction, which led to tanks getting bogged down. Special grousers were created to solve this issue that were attached on every other track link. The grouser was wider than the track links, so it doubled as a track extender. These grousers were first used on Mark II tanks, but they can also be seen on later models. The grousers were not used on medium tanks at all and do not appear on British inter-war tanks.