How Dale could have beat Mordor: 

Send tons of cavelry around the side of Mordor through the Eastern Desolation, attacking Nurn in the side and destroying it's production. Sauron would have to send all their troops to Nurn to stop Dale and in that time Gondor could have swooped in and detroyed Mordor. 

When you think of this, Khand and the Golden Khanganate both have Mordor on a knife's edge. Cool if they used this advantage and suprise attacked Sauron :P

Ye, I mean the free Easterlings could have attacked nurn which makes more sense

Mirkwood was attacked when Erebor was raided, right? They could not send troops.

A reply to Legoarmy:

Sauron probably did enlist Easterlings to attack Dale. However, simply put, it's speculated the Blue Wizards foiled this plan.

Smaug, however, probably would not listen to Sauron. It's fairly certain only Morgoth himself controlled the dragons.

As for your second point... Easterlings never took Erebor or Dale.

As you can see, no stupid mistakes where made, but rather Sauron was inconvenienced.

Yeah the battle under the trees, a massive army was send in from Dol Guldur in the south to engage the Sylvan forces and the beornings. They fought a war under the cover of the forest for several days untill eventually the elves knowledge of hte forest outdid the brawn of hte orcs and they utterly anihilated them leaving none to return to Dol guldur. The other armies dol guldur send out were to Lothlorien, they crossed the anduin up north and then came south to attack the forest, joined by an even bigger army of orcs from moria. The attacks were repelled though and barely any were left alive giving the Galadhrim the chance to deploy their ships on the river, sail across in no time and quickly march upon the fortress casting down it's walls and clearing it's foul pits.

I knew that, but at the same time Erebor was attacked?

And thx for the information :)

The free Easterlings could not control the north west area of rhun unless during the war of the ring they were destroyed before Easterlings sieges erebor. I do believe that sauron was still mustering troops from there so he may not want to spend them.

Smaug is a dragon who would listen to morgorth but Sauron was morgorth's right hand man and had control over many other Maia which are superior to Smaug. But you could say Sauron was still getting strength so Smaug won't follow him.

Also, the bane of durin, once he was awoken, Gandalf knew about him so Sauron must have too. Sauron would have been better by placing him in mordor and just sending more troops to khazad - dum as well as having a fake Barlog made of poles, thin fabric and lots of lanterns

Durin's Bane anwsered only to Morgoth he was simply waiting and hiding out for his master.