That primitive arms race has continued down to our times, but since people have trouble taking the 'long view', we tend to perceive a series of arms races rather than just one. Arms races are nothing more than a search for advantage in the technical arena. Faster, stronger, more powerful, higher. Any potential advantage will be closely inspected to see if it will be of value in combat. Tanks were the result of the search for mobile firepower combined with adequate protection for the crew.
It could be argued that siege towers of the classical and medieval periods were the forerunners to our modern tanks. They were mobile, (for, possibly, several hundred yards to reach the fortress walls!) They provided protection for their 'crews', and they carried various forms of firepower, from personal weapons to small ballistae. They were only a hint of modern tanks, however, for once they reached the walls, they never moved again, regardless of the outcome.
The first tank conceptualized with a hope for true battlefield mobility was probably the armored car designed by Leonardo Da Vinci. Armored for crew protection and mounted on wheels for mobility, it was conceived as a roving fortress, but no attempt was ever made to build one. World War One brought the first (successful) tanks. Even these were not highly successful, though. They were under powered, inadequately armed, and their use was so misunderstood that their advantage was frittered away.
Success is a relative thing, though. The first battlefield use of tanks near Cambrai by the British was conceived as making use of the 'terror' aspect of the new vehicle. It worked. German troops panicked when faced with the new, apparently impervious vehicle, and its use was highly successful. Greater success was missed, though, because of insufficient support, and the attack finally bogged down from its own inertia, even though the enemy lines had been broken. These early tanks were used as infantry support weapons, because no one had yet conceived that they could operate as a separate force. They were armed with a variety of weapons, usually a large selection of machine guns and, frequently, a small field gun. Crews numbered as many as twenty two in some versions. These early behemoths were ungainly, difficult to maneuver, and suffered from frequent breakdowns.
