Halo 3 - Floodgate

The level takes place in Voi, Kenya on the continent of Africa on Earth during the Battle of Earth. Floodgate is the first campaign mission where Sangheili allies other than Thel 'Vadam are encountered in Halo 3. It is also one of the shortest levels in the game. Shortly after John-117 disabled the Covenant Anti-Aircraft Battery in the previous level, The Storm, UNSC Frigates under the command of Lord Terrence Hood attacked the Covenant controlled Forerunner dreadnought. This assault failed, as the Dreadnought survived unscathed. The Covenant Loyalists then activated a Portal to the Ark, temporarily disabling the Frigates. The remnants of the Covenant Loyalist fleet then followed the Dreadnought into the Portal. With the UNSC fleet disabled, and the Anti-Aircraft Battery out of commission; the Flood-infested Indulgence of Conviction suddenly jumped out of Slipspace nearby and crashed near the Traxus Factory Complex 09.[2] Immediately after the crash of the Flood-loaded battlecruiser, the infection spreads around the city, infecting everything in its grasp. In order to eliminate the infestation, John-117 and Thel 'Vadam had to overload the crashed cruiser's engines, wiping out the entire city and the Flood with it. To do this, they pushed back through the factory where they just came from, fighting many Flood Combat Forms and new Pure Forms, and if possible, saving what UNSC Marines they could before they could be killed and/or mutated into more Flood Combat Forms. They were then aided by the arrival of Rtas 'Vadum and a Covenant Separatist fleet. 'Vadam and John, along with a Sangheili strike team, pushed forward to the crashed ship. John-117 was later informed by Miranda and Johnson that the Elites "found" Cortana in the ship, and tasked him to recover her. Thel and the rest of the strike force stayed outside to ensure nothing would enter and attack John-117 while he was in the ship. John eventually found Cortana, but it was just a recording. A Combat Form inside surprised him, but was quickly taken down by 343 Guilty Spark. The two were later extracted from the ship. Once on board the Separatist Assault Carrier, Shadow of Intent, 343 Guilty Spark extracted Cortana's recorded message from the Covenant storage device. This message informed everyone about the Flood-infested High Charity making its way towards Earth, and that there was a way to stop the Flood. Hood, concerned with Cortana due to her rampancy, decided to bunker Earth's defenses, which Rtas protested as the humans barely survived a small infestation. John and Miranda managed to convince Hood to send forces through to the Portal to stop both Truth and the Flood. During this time, the Separatist fleet glasses Voi and the surrounding area to ensure there were no Flood left on Earth.