That's not even one of Uglúk's faults

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Regarding trees and Uglúk's last stand, here is the text that makes me think as I do (emphasis mine):

Originally Posted by TTT:The Uruk Hai

The Isengarders began to run with a redoubled pace that astonished Pippin, a terrific spurt it seemed for the end of a race. Then he saw that the sun was sinking, falling behind the Misty Mountains; shadows reached over the land. The soldiers of Mordor lifted their heads and also began to put on speed. The forest was dark and close. Already they had passed a few outlying trees. The land was beginning to slope upwards, ever more steeply; but the orcs did not halt. Both Uglúk and Grishnákh shouted, spurring them to a last effort.

Before the orcs make their last camp upon the hillock, they already have encountered trees, and the ground in sloping upward in the direction that they wish to go (and later try to escape).

The eaves of the forest were very near, probably no more than three furlongs away, but they could go no further. The horsemen had encircled them. A small band disobeyed Uglúk's command, and ran on towards the forest: only three returned.

The edge of the forest, even though we already have trees, is only ~660 yards or 603 meters away at most. And did I mention 'sloping?'

Then with a great cry the Riders charged from the East; the red light gleamed on mail and spear. The Orcs yelled and shot all the arrows that remained to them. The hobbits saw several horsemen fall; but their line held on up the hill and over it, and wheeled round and charged again. Most of the raiders that were left alive then broke and fled, this way and that, pursued one by one to the death. But one band, holding together in a black wedge, drove resolutely in the direction of the forest. Straight up the slope they charged towards the watchers. Now they were drawing near, and it seemed certain that they would escape: they had already hewn down three Riders that barred their way.

We have Uglúk and his mates trying to escape to the forest, uphill with some tree cover. Three Riders - not Rohirrim, or men, but Riders were hewn down by the orcs. Doesn't Eomer lose a total of 15 men during the whole affair, and here in this brief moment he loses 20% of the total, and that because of a "band?" To me, this means that not only were these orcs the best of the bunch, but also that they had some advantage.