Why is this movement significant? It was the first chronograph for the wristwatch.

I’m not sure how more monumental this can be. Consider that the chronograph function was, prior to 1913, restricted to pocket watches. In order to actually use the chronograph and keep track of elapsed time, you would need to hold the pocket watch in one hand. But what if you’re faced with a situation where you might need a chronograph and the use of both your hands (perhaps to fly a plane or hold a rifle), it would be a lot more effective to have a chronograph on one's wrist.

It is hence no coincidence that the first of these watches were meant for military use. History gives us a reason for these developments – we're talking about the period leading up to World War I.