The Sino-Indian War (also known as the 'SI War') was a devastating conflict that occured on the planet Earth before the arrival of the Taelons.
It was during this time that special forces units were known to implant surgical breathing tools inside their body to allow them to counteract the effects of gas attacks. One noted engagement was the storming of the Shanghai Nuclear facility by Major Raymond McIntyre. (Episode: Live Free or Die) At some point in the conflict, there was an invasion of Taiwan which Liam Neville Kincaid participated in where faulty intelligence left his unit trapped in a brutal ambush. The entire platoon was killed except for two survivors namely Liam Kincaid and William Boone. (Episode: Message in a Bottle) Another notable engagement during the war was the Battle of Kashmir. (Episode: Deja Vu) The conflict also spilled into Tibet at some point with the Chinese as well as India being several of the factions present in the war. Both government were disarmed of their arsenal though some believed that they would eventually resume hostilities whilst others in the US government felt that they had the strength to enforce and keep the peace. (Episode: Scorched Earth)
During the time of the SI War, gallant Colonel Dennis Roberlard and Captain Samira Farid participated as covert operatives in the conflict with the intention of stopping nuclear devastation. Whilst nuclear war was averted, Captain Farid was killed when an unknown weapon - later called the Quantum Vortex, was detonated. It was the use of this weapon that ultimately ended the SI War. Ronald Sandoval was involved in the war but only participated as an intelligence agent and thus was not involved overseas. (Episode: Scorched Earth)
Eli Hanson, a notable journalist, was known to had participated in the conflict and served as a reporter at the time. (Episode: The Cloister) The newly born Human-Kimera hybrid Liam Kincaid orchestrated his own personal history and claimed to Ronald Sandoval that he had fought in the SI War alonside William Boone. (Episode: The First of its Kind)
In the French version of the show, the S.I. War is always referred to as the "Southern Islands War" (la Guerre des îles du sud).