It is not a surprise that Lorien was a difficult place to attack. Dark
dense forest filled with nearly stealthy invisible elvish archers with unerring
accuracy. Any army going in there would have been masacred unless
accompanied by some strong magic.
Any idea on who led the attacks by Don Guldur? I cant believe Sauron
would have left an orc chiefton in charge of an attack against Galadriel..the
most powerful elf in middle earth armed with one of the three rings. I
once heard that this was supposed to be the Balrog's post before he was taken
down prematurely by
Gandalf.