Palpatine's death in ROTJ apparently unraveled the entire Empire proper: {from the novel} "For the Emperor was dead. The central, powerful evil that had been the cohesive force to the Empire was gone; and when the dark side was this diffused, this nondirected—this is simply where it led. Confusion. Desperation. Damp fear.”
Ooh, and Palpatine's death "diffused" the dark side. Forgot all about that.
Sidious is apparently capable of Force Multitasking. His Battle Meditation was in fact active through the entire 2nd Death Star confrontation, and the Empire was winning right up till he bought it...then the Empire's troops fell apart.
OP said "Battle Mediator" and many responses have been about Battle Meditation, so which one are we discussing here?
Meditate and Mediate aren't the same thing.
__________________ "You must begin by gaining power over yourself; then another; then a group, an order, a world, a species, a group of species... finally, the galaxy itself."
- Darth Plagueis
"She may be small but she packs a punch and when shes in this mood...she goes for my danglers" - Oghren, Dragon Age
Yeah that's the reason why THRAWN wanted JORUUS C'BAOTH. A Jedi master capable of Battle Meditation was something he needed and he made note on how the Battle of Endor was going well until the Emperor dies and makes the connection that it was Palpatine's existence helping them.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."