Final answer:
The author supports the statement by explaining how the introduction of new technologies in World War I made defending from trenches more effective than charging the enemy's position, illustrating the futility and high cost of life in charging across no man's land, and providing an example of a British attack that temporarily gained territory but with significant casualties.
Step-by-step explanation:
The author supports the statement that "trenches become a necessity as well as a strategy for winning war" in several ways:
- The introduction of new technologies in World War I, such as machine guns, mines, and modern rifles, made it more effective to defend a position from trenches rather than charge and try to take the enemy's position.
- The British phrase "going over the top" describes the futility of charging across no man's land, where the enemy in the trenches could open fire with impunity, resulting in a high loss of life with little territorial gain.
- The example of a British attack in 1915 that gained temporary territory at the cost of thousands of lives highlights the difficulty of breaking through the trench system.