Complex sentence: The campaign starts 15 years after the formation of the network; it is precipitated by the unrest of extremists in both factions, which sparks the Fourth Tiberium War and ends the alliance.
Split into simpler sentences: The campaign starts 15 years after the formation of the network. It is precipitated by the unrest of extremists in both factions, which sparks the Fourth Tiberium War and ends the alliance.