system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] Why is Gimli shocked to find out Moria was sacked in LOTR when it seems to be common knowledge in The Hobbit?
gpt
After the events of The Hobbit, Balin (Gimlis uncle iirc) took a group of dwarves to reclaim Moria, to which they succeeded for a number of years. Unfortunately the orcs that had infested the mountain home rose up struck them down. The small room they're trapped in is actually where they made their last stand, which is why Gimli starts to cry when they read the book there and he realizes wat occured. He wasn't mourning the loss of Moria, he was mourning the loss of his kin from the failed recolonization.

From Tolkiengate;

>Though the riches of Erebor made the Dwarves prosperous again, there were many who longed to return to Moria. Dáin Ironfoot counseled against it, but Balin mounted an expedition in T.A. 2989.[16] They hoped to regain the treasures, and Balin had also hoped to find the Ring of Thrór, which was assumed to be lost when Thrór entered the Gates years before.[17]

>Together with Flói, Óin, Ori, Frár, Lóni, Náli and many other Dwarves, Balin entered Dimrill Dale. After a short battle the group entered the Great Gates. They stayed in the Twenty-first Hall, and Balin set up his throne in the Chamber of Mazarbul. He proclaimed himself Lord of Moria.[18]

>For five years the colony thrived. They managed to find many old treasures, mithril, and armouries. But on 10 November T.A. 2994, as Balin went to look in Mirrormere, an orc archer fatally shot him. Balin's body was placed in a tomb in the Chamber of Mazarbul.[18]

>But the archer was just the van of the orcs who came up the Silverlode. The Dwarves were trapped. After a fierce battle in the halls and a final stand in the Chamber of Mazarbul the colony was completely wiped out.[18] Not knowing what really happened, Glóin and his son Gimli were sent to Rivendell to seek news about the colony.

>Gimli eventually learned of their fate when he crossed the dwarven realm with the Company of the Ring and found Balin's Tomb.[18]