This is the Hour
From Halopedia, the Halo wiki
This is the Hour is a song included in the Halo 3: Original Soundtrack. It is one of the most recognizable themes in the entire game. It is actualy the song heared in the Halo 3 E3 video.
The song plays during the ending cutscene of The Storm.
The very beginning is mainly choir, followed by the well-known piano motif. This is then repeated by the entire orchestra. The song swells to a dramatic climax, then abruptly stops.
It runs for 2:06.
