Truce of Tukayyid
With the victory of ComStar's military arm, the ComGuards, against the invading Clans in the Battle of Tukayyid, the Clans had to abide by the Truce of Tukayyid, sometimes known as the Treaty of Tukayyid, a 15 year (3052 to 3067) truce with the Inner Sphere in which no Clan elements would cross the plane emanating from the planet of Tukayyid and extending to the edges of the Inner Sphere perpendicular to the Clan Occupation Zones.
The Battle of Tukayyid
While initially attempting to neutrally serve the Clans as they did the Inner Sphere powers, upon learning their intention to capture Terra, Precentor Martial Anastasius Focht met with ilKhan Ulric Kerensky to organize a proxy battle on the Free Rasalhague Republic agricultural world of Tukayyid for control of the cradle of humanity. If the ComGuard lost, ComStar would join the invaders and Terra would be theirs. If however ComStar won, the Clans would not advance any further towards Terra than Tukayyid for 15 years.
The actual battle was broken down into ComGuard-defended objectives that the Clans would try to conquer. Save for Clan Wolf, the majority of the Clans once again anticipated an easy battle and swift victory. However Focht had not been idle during his time with them and had correctly predicted that the Clan style of fighting favored short battles with little concern towards any ability to withstand a long term engagement. Planning his defense carefully, Focht stockpiled enough stores to supply his troops for more than a month and ordered his forces to harass the Clans, rather than commit to a direct confrontation. Despite their relative inexperience and heavy losses, the ComGuards slowly wore the Clans down, and after 21 days of bitter fighting had won the battle.
For the Clans the truce would have devastating effects, along with a massive escalation of the conflict between the Warden and Crusader factions. Unlike the Inner Sphere, the Clans cycled their warriors through at a very high rate and by the time the truce ended in 3067 the warriors who had served in the Clans' frontline Galaxies at the time of the invasion would be long retired. Having fought in the initial invasion these warriors had gotten a taste for true all-out war and became increasingly dissatisfied with the state of peace they now found themselves in and the prospect of being disgraced older warriors who wouldn't see action outside of Solahma units at truce end.
At the other end of the cycle, three generations of Clan warriors would enter service and know nothing of warfare except trials, exercises and the occasional raid. These relatively untested warriors would be facing Inner Sphere troops, many of whom would have seen action during the invasion, piloting upgraded 'Mechs almost equal to Clan designs.
The dissatisfaction against the Truce focused on Ulric, despite the fact the Grand Council all voted in favor of its terms, ultimately leading to a charge against him of treason and genetic genocide against the Clan way of life, culminating in the Refusal War. As the Warden Clans had hoped, the truce led to a fragmentation of the Clans' purpose and prevented their Crusader brethren from denying the Inner Sphere the respite the truce represented.
While the result was unthinkable for the Clans, the truce was not a perfect solution for the Inner Sphere powers either. The truce merely prevented the Clans from approaching any closer to Terra than Tukayyid, leaving numerous worlds above the truce line, including the Draconis Combine's capital of Luthien, open to attack. While the truce bought the Inner Sphere powers time to rebuild and upgrade their shattered forces, the ending of the immediate conflict shattered the unification that the invasion had triggered and old conflicts returned to the fore. Even the ComGuards and Focht, at first lauded as heroes, were tainted by the actions of Operation SCORPION.
It took the Invasion of Coventry by Clan Jade Falcon in 3058 to finally force the Great Houses to start working together toward a more permanent solution: the reformation of the Star League for the express purpose of ending the Clan threat, once and for all. To prove themselves a force to be reckoned with the new Star League chose to destroy Clan Smoke Jaguar. Initially, the Star League intended only to drive the Jaguars out of their occupation zone but information from a Smoke Jaguar traitor enabled them to strike at Jaguar's homeworld of Huntress as well.
After utterly destroying the Smoke Jaguars in 3060, the reformed SLDF force led by Victor Steiner-Davion traveled to the Clan capitol Strana Mechty and defeated the Crusader Clans in a Trial of Refusal, ending the Clan Invasion with seven years to spare.