Renegade Crisis
From FABT
The Renegade Crisis, also known as the Krogan Crisis, was a series of interrelated diplomatic and military escalations between the Citadel Council, the states that form up the Council and the Tuchankan Empire that started on 12 May 86 CE when the Tuchankan Empire first began its aggressive expansions throughout the galaxy and ended with their total military defeat at the end of the Krogan Rebellions. The crisis was ultimately the result of post-Rachni Wars tensions, with the newly established Tuchankan Empire now finding itself in control of a large swath of territory that it either refused to give up or wanted more of. The crisis itself is named for the infamous krogan warlord Juntor Moro, who the Council dubbed "the Renegade" due to the Empire's inability (or lack of desire) to control him: Moro's policy of Jebreksad emphasized the krogan's need to constantly expand in order to give breathing room for their ever increasing population, and although the Empire at times claimed to be in opposition to Moro's actions, they made no effort to control the warlord, and were caught numerous times funding his efforts. By 400 CE, the Empire ceased all illusions of not supporting Moro's actions, and threatened severe military retaliation against the Council if they chose to intervene; as a result of this, the Council was forced to rely on economic sanctions and tariffs as punitive measures.
Despite being named for Moro, the crisis itself centered around the greater Council-Tuchankan diplomatic relations, and is also known as the Krogan Crisis by Council historians. Moro's actions defined the majority of the crisis however, with his ruthless military expansions, intimidation and strongarming of former allies, piecemeal annexations and constant provocation of the Council being labelled as the face of the greater crisis. New races joining the galactic community around the time, such as the quarians and hanar, were constantly harassed by the krogan in an attempt to turn them into protectorates or vassals of the Tuchankan Empire, efforts of which failed when the hanar and quarians joined the Citadel Council. A border war between the quarians and krogan was sparked as a result of this refusal to forfeit their sovereignty, a war which ended in a stalemate when Moro decided to withdraw. The Council attempted to bankroll a coup d'etat in 690 CE against the Tuchankan government utilizing a small rebel movement who opposed Moro's actions, but this rebellion was swiftly crushed and the rebels massacred. Having run out of available territory to conquer, Moro eventually began annexing Council-held worlds, starting with claims and escalating to populated planets, initially delivering ultimatums to these worlds for their populations to evacuate, before choosing to enslave the populaces. The Council finally summoned Moro to the Citadel in early 700 CE to deliver an ultimatum of their own: do not annex Lusia, or they will retaliate militarily. Moro then brazenly annexed Lusia, slaughtering the entire population out of spite, and shortly after, the Council declared war on the Tuchankan Empire, starting the Krogan Rebellions.
The Renegade Crisis did not officially end until the conclusion of the Krogan Rebellions, with the demilitarization of the krogan home territory and deployment of the genophage. The war saw the deaths of Moro and most of the krogan's other powerful warlords, the complete dismantling of their military, the neutering of their population to containable levels, and a massive reduction in their territory to just one cluster. As per the Treaty of Taetrus, the krogan were prohibited from fielding a navy, had to give up their entire nuclear and antimatter arsenal and were not allowed to develop further weapons of this class, were not allowed to claim or own territory, had to pay 700 trillion credits in reparations to all Council races affected by the war, recognize vorcha independence and accept responsibility for starting the war. This left the krogan beaten and humiliated, stripped of their former power and status and reduced to a mere echo of the threat they had once posed. The Council did not intervene when the Krogan Civil Wars broke out, believing that so long as it did not spill over into Council space that it wasn't deserving of intervention. It wouldn't be for another thousand years before the genophage was cured in 2186 CE, and the New Council dissolved the Treaty of Taetrus.