<p>A reply to Legoarmy:
</p><p>Sauron probably did enlist Easterlings to attack Dale. However, simply put, it's speculated the Blue Wizards foiled this plan.
</p><p>Smaug, however, probably would not listen to Sauron. It's fairly certain only Morgoth himself controlled the dragons.
</p><p>As for your second point... Easterlings never took Erebor or Dale.
</p><p>As you can see, no stupid mistakes where made, but rather Sauron was inconvenienced.
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