[steve]

If Smaug was not destroyed in the Hobbit it could and would have caused many many problems for the alliance against Mordor. Just of the few things that could have been done if Sauron has Smaug under his controll... As mentioned the destruction of Eriador. Also, smaug could have been used, as well as the ringwraiths to kill frodo and the fellowship. Also, even if the elvs could see Smaug's weakspot, what is to say that they would see it before he has the entire forests of Lothlorien or Mirkwood ablaze? Smaug could have been used to destroy Fangorn forest, therefor insuring the survival of isengard and the destruction of Rohan (as sad as that is to say) Then there is the inevitable, Smaug at Minas Tirith. But yet, these are only if Sauron would do the obvious thing with Smaug... if Sauron had controll of Smaug and was smart he would do something along the lines of destroying Dunharrow after the evacuation of Edoras, or Destroying Dol Amaroth and the outlaying Gondorian citys preverntion any reinforcments reaching Minas tirith. Who knows, Smaug could have saved Dol-Guldur or stoped the advancing armies outside of Mordor's black gates therefor making the nazgul and or any other dark being sauron wanted, to stop frodo at mount doom... and these are just a few sugeustions