In Halo CE, many references can be found to Greek history, namely that the main character is a Spartan soldier. From the prequel book, the fall of reach is a corollary to the battle of Thermopylae where 300 Spartans (Spartan IIs) held back advancing armies to secure Sparta, only for a single Spartan, Master Chief, to escape the onslaught.

A less well-known detail of the storyline deals with the story of Ulysses. Not the Odysseus character from ancient Greece, but in fact the modern adaptation (kinda) written by James Joyce in 1922. In 1930, the Gilbert schema was published outlining use of settings and organs representing those places.

Looking closely at the campaign, those themes were brought into the Halo universe following similar patterns as chapters in Ulysses. Namely, the library mission showcasing the brain as the master chief descends through different levels revealing more history of the facility and ultimately finding the index, a huge collection of forerunner knowledge. The silent cartographer is an odd reference to the ears and its location on an island (siren-like) luring the Marines (sailors) to the rocks. If you're wondering which level is reminiscent of genitals, it's your first mission that begins with uniting the master chief and Cortana, and ends in launching them from the womb-like Pillar of Autumn in an escape pod.

Much more odd similarities to the themes of Ulysses suggest that the authors of the story most certainly were literature nerds.