Medieval Chess What Gives The Queen The Right To Be So Powerful On The Chessboard?

What gives the queen the right to be so powerful on the chessboard? - medieval chess

I'm beginning to fail, so I'm curious.
If chess is in the style of a medieval army, the queen of the Board / battlefield in the first place? Queens are not usually sit in the castle, to move at least a couple of soldiers, but during the battle guarded?