What would the numeric tempo range be for a march marked "agitato"?
Agitato is an indication of character not speed. As Mark points out it means agitated or aggressive but that does not mean that it is inherently fast.
You have the third movement from the Moonlight Sonata that is Presto Agitato
This song from the soundtrack of Interview with the Vampire shows a piece that is Allegro Agitato just to illustrate that the mere fact that there is an indcation of Agitato does not necessarily mean fast.
"Agitato" is not exactly a speed. It means "agitated" and generally means that the speed will be faster than normal -- it's more a relative speed than an absolute speed. But really it's more of a mood or feeling than a speed.
A typical tempo for a standard parade march is 112. I can picture a band marching to that tempo in a Fourth of July parade, but I'm having trouble picturing a band marching "agitatedly". Maybe the enemy is advancing directly behind them?
If that were the case I guess they would be doing a Quick March. Try 140 bpm which is typical Quick March tempo and see how that works.