Tanks
In 1915 Europe was in the midst of World War I and was at a stalemate caused by trench warfare. There was a need for new and revolutionary weapons to end the dilemma. The British found a solution to this problem by inventing tanks. The invention of the tank had numerous pros and cons, but it ultimately changed warfare.
Tanks were built for the purpose of traversing through trenches. Trenches were becoming a literal wall and prevented either side from advancing. Tanks were the solution to the predicament that was the Western Front. The first prototype was called Mark I and was tested for the British Army in the September of 1916.
Tanks were progressive and enabled many new tactics. They used caterpillar tracks