Skill-Out Uprising

TheSkill-Out Uprising are a series of events carried out by Komaba Ritoku's Skill-Out gang, and would have culminated in Skill-Out's disabling Academy City's communication network allowing them to attack target espers.

The plan fails after the death of Komaba Ritoku and the turning over of power of his gang to Hamazura Shiage.

Aftermath of the invasion
After the failed invasion of Academy City by the Roman Catholic Church under Vento of the Front, hostilities between the two forces have increased and the likelihood of war has become apparent, and now sides are begun their preparations for it.

However, because of Acadeny City's strengthening of their defenses against outside forces, the defenses within the city has considerably weakened, so much so that Komaba Ritoku and his Skill-Out gang can take advantage of it.

Trivia

 * With only 1 and half episodes dedicated to covering the event (as the other half was dedicated with still covering the epilogue of the invasion), the Skill-Out Uprising, or more specifically the Toaru Majutsu no Index Light Novel Volume SS has the shortest adaptation of an event in the anime.