What is the term for taking the initiative and maintaining momentum in military operations?

The term that best describes taking the initiative and maintaining momentum in military operations is "Offensive." In a military context, an offensive refers to operations designed to take control and push the enemy back, ultimately seizing the initiative in the conflict. An offensive approach typically involves aggressive tactics, with the goal of disrupting enemy plans and gaining an advantageous position. This embodies the characteristic of initiative, as forces actively engage rather than waiting for the enemy to act.

While "Proactive" suggests a similar idea of taking action rather than a reactive approach, it is a more general term that can apply to various fields beyond military operations. "Advance" typically focuses on the movement of troops forward and may not necessarily imply the broader strategic control and initiative associated with an offensive. "Assault" refers more specifically to a focused attack on a particular position and lacks the overarching emphasis on maintaining momentum across a broader scope of operations that the term "offensive" entails.