What prophecies did Bahaullah fulfill?
Countless prophecies.
Just to begin with, Jesus said he would return in the Glory of the Father:
"For the Son of man shall come in the glory of his Father" - Matthew 16:27
The name Baha'u'llah, translated into English means the Glory of the Father, or the Glory of God.
Here's one from Isaiah 35:1-2:
"The wilderness and the solitary place shall be glad for them; and the desert shall rejoice, and blossom as the rose.
"It shall blossom abundantly, and rejoice even with joy and singing: the glory of Lebanon shall be given unto it, the excellency of Carmel and Sharon, they shall see the glory of the LORD, and the excellency of our God."
Baha'u'llah was banished and imprisoned, finally being moved to the penal colony of Akka, certainly a "solitary place" on the edge of the Ottoman Empire (now in Northern Israel). He visited Mount Carmel numerous times (just a few miles from Akka) which is the edge of the plain of Sharon, which is now in Haifa, Israel. On Carmel He pitched His tent and outlined the spot where the Shrine of His Herald the Bab was to be built and the Baha'i institutions were to be raised. Now there are terraces and gardens build on Mount Carmel, and the Baha'i Administrative Order is headquartered in a series of beautiful buildings:
https://www.google.com/search?q=baha'i+carmel
http://www.tacomabahai.org/wp-content/uploads/2009/05/bahji-77.jpg
Throughout the Bible, there are a very large number of references to 1260 days. And in the Bible, each prophetic day is to be considered as a year:
"And your children shall wander in the wilderness forty years
.after the number of the days in which you searched the land, even forty days, each day for a year." - Numbers 14:34
"And when thou hast accomplished them, lie again on thy right side, and thou shalt bear the iniquity of the house of Judah forty days: I have appointed thee each day for a year." - Ezekiel 4:6
There is probably no more important prophetic number referenced than these 1260 days. It is variously referred to "1260 days", "three and a half times" (each "time" is a year of 360 days, 3.5 x 360 = 1260), "a time, times and half a time" (again, 3 1/2 times) "42 months = 42 x 30 = 1260"
Here are the seven references:
"He shall speak great words against the Most High, and shall wear out the saints of the Most High, and think to change times and laws -- and they shall be given into his hands until a time and times and the dividing of a time." - Daniel 7:25
"It shall be for a time, times, and half a time that he can scatter the power of the holy people." - Daniel 12:7
"The holy city they tread under foot forty and two months." - Revelation 11:2
"And I will give power unto my two witnesses, and they shall prophecy a thousand two hundred and sixty days, clothed in sackcloth." - Revelation 11:3
"And the woman fled into the wilderness, where she hath a place prepared by God, that they should feed her there a thousand two hundred and sixty days." - Revelation 12:6
"And the woman was given wings of a great eagle, that she might fly into the wilderness, where she is nourished for a time, and times, and half a time, from the face of the serpent." - Revelation 12:14
"And there was given to the beast a mouth speaking great things and blasphemies, and power was given to him to continue forty and two months." - Revelation 13:5
So it is very clear that 1260 days is a VERY important number in the Bible, covered in the Old Testament and the new.
In the lands where the books of the Bible was revealed, the year was reckoned as 1260 (AH) when the Baha'i era began with the declaration of the Bab, Herald of Baha'u'llah (1844 AD). This is also the year that millions of Christians, led by William Miller, were expecting the return of Christ, based on other prophecies in Daniel that were specifically referenced by Jesus as indicating the time of His return:
Great Disappointment - Wikipedia, the free encyclopedia
They were "disappointed" because they looked up into the sky for Jesus to return in that year. But maybe that is because He "returned" in the same way Elijah "returned" before the coming of the Messiah, instead of flying down from outer space the way many Christians imagined would happen.