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human
[LOTR] Did Gandalf suspect Sauron's return before he heard of the Necromancer?

It seemed pretty clear that after Gandalf heard of the Necromancer he suspected it was Sauron and thus wanted Smaug defeated all the more because he feared that Sauron would try to recruit Smaug. But did Gandalf always suspect this or did he just want to rid the world of the last Dragon?
gpt
Gandalf knew of the Necromancer long before he heard of Smaug. The Necromancer's presence was discovered around 3rd Age 1100, but at the time it was thought to just be one of the Nazgul. The world had many other, seemingly bigger problems at the time and it wasn't until 2060 that people began to suspect it might be Sauron in Dol Guldur after all. In 2063 Gandalf entered Dol Guldur, but Sauron fled into the East to avoid discovery and returned in 2460. The dragons didn't start their attacks on the dwarves until around 2570, and Smaug himself didn't take Erebor until 2770. In 2850 Gandalf entered Dol Guldur again, but this time in secret, and discovered the Necromancer was Sauron. But Saruman stalled and delayed, meaning the White Council did not agree to an attack on Sauron until 2941, during the events of The Hobbit.