Final answer:
A rocket artillery unit can only reinforce an infantry unit. Tanks were introduced in 1916 to support infantry during World War I and had a significant impact on changing the nature of warfare.
Step-by-step explanation:
The Rocket Artillery Unit
A rocket artillery unit can only reinforce an infantry unit. In 1916, the British introduced tanks as a support for infantry during World War I. Tanks were mobile and could travel with advancing infantry, providing a significant advantage. While tanks were not considered artillery units, they played a crucial role in changing the nature of warfare.