When looking at Gettysburg day one and two, the lack of major cavalry support on both sides is always startling.
Well the Union cavalry was certainly involved in the initial stage of the battle.
The second day, and the 20th Maine's defense of Little Round Top is an inspiration of leadership and courage.
To me, as soldier, this battle was really an interesting collection of loosely-associated, small-unit actions, any of which, going the other way, would have changed the course of history.
Gettysburg was truly a nexus of AMerican and world history.