Final answer:
Tanks were used as armored vehicles in battle, but were said to be used for carrying water to soldiers on the battlefield to keep their purpose a secret.
Step-by-step explanation:
The real purpose of tanks during World War I was to be used as armored vehicles in battle. However, to keep their purpose a secret, they were said to be used for carrying water to soldiers on the battlefield. This was done to mislead the enemy and maintain the element of surprise. Tanks were designed as a weapon of war to provide protection to soldiers and break through enemy defenses, not for carrying supplies or soldiers into battle.
Learn more about the purpose of tanks during World War I