Armoured trains appeared in the mid-19th century and various armoured steam- and gasoline-engined vehicles were also proposed. The first armoured car was produced in Austria in 1904. However, all such vehicles were restricted to rails or reasonably passable terrain. It was the development of a practical caterpillar track that enabled independent, all-terrain mobility around the trenches and shell-battered landscapes of WWI.
The caterpillar track originated out of attempts to improve the mobility of wheeled vehicles by spreading their weight and increasing their adhesive friction. Experiments can be traced back as far as the 17th century; by the late nineteenth century they existed in various recognizable and practical forms in several countries.
It is frequently claimed that Richard Lovell Edgeworth created a caterpillar track. He patented a "machine, that should carry and lay down its own road" in 1770, but his own account in his autobiography is of a horse-drawn wooden carriage on eight retractable legs, capable of lifting itself over high walls. The description bears no similarity to a caterpillar track.
The British were the first to develop a military tank, a response in 1915 to the ongoing stalemate on the Western Front. The French also developed tanks in 1917, but the Germans were slow to respond. They focused on developing anti-tank weapons, with mixed results. While the tanks were slow, with a top speed of about 4 mph, and many had design flaws that caused them to become stuck in the trenches, a few models, such as the French FT and the British Mark series, worked very well and allowed their operators to penetrate the German trenches.