The Vilno Gaon on Moshiach

Not that we need additional proofs but the GR”A (VILNA GAON) writes: (Kol HaTor, Ch. 2 par. 75, Ch. 2:2, 4:1)

1. Moshiach Ben Yosef will teach Penimiyus HaTorah √
2. Reach out to non-Jews √
3. In general, begin the preparations for the redemption √
4. Will die before he completes the process … √
5. At that point, a period of darkness and confusion will ensue. √
6. The nations, particularly Yishmael, will descend upon Israel and Jerusalem. √

"When the situation seems hopeless, Moshiach ben Dovid will appear to resurrect Moshiach ben Yosef, and the process of redemption will be completed by them both”
Moshiach Ben David and Moshiach Ben Yosef ARE NOT two separate Moshiachs at all. According to such notables as Rav Chaim Vital, Moshiach ben David and Moshiach ben Yosef are merely terms that represent different aspects of one and the same individual! (Sefer Chizyonos p. 106). We are left with the following scenario: One Moshiach will arise to prepare the world for redemption for forty years after which he will die, only to return in resurrection to complete the job.