Which military branch is usually deployed first?

Hi everyone, I've been doing a bit of research into the military and I was wondering which branch usually gets sent to war first? I've heard some vague stuff but nothing definitive, so if anyone could provide some insight it would be super helpful.

In general, the U.S. military branch that is typically deployed first during a conflict is the United States Marine Corps, as they have traditionally been known as the tip of the spear when it comes to immediate response situations.

This is largely due to their operational doctrine, which calls for them to be the rapid reaction force that leads the way for larger, sustainment forces like the Army. However, this doesn't mean that every conflict begins with the Marines.

The branch tasked with initial deployment can depend on the nature of the conflict, the geographic location, the specific goals of the operation, and the current global military posture at the time. The Coast Guard, for instance, could be the first deployed in a maritime dispute near U.S. waters. In another scenario, the Air Force might be first to respond if air superiority is a crucial initial objective. So, while generally the Marines have held the role of being first to deploy in many historical situations, it does fluctify based on numerous factors and scenarios.