Complex sentence: A tonnage war, however, is a very broad strategy, and does not require that the attacker establish control over any particular area, merely that he sink ships more rapidly than the defender can replace them.
Split into simpler sentences: A tonnage war, however, is a very broad strategy. As a form of attrition warfare, it does not require that the attacker establish control over any particular area, merely that he sink ships more rapidly than the defender can replace them.