Fun fact: The show itself is canon, it's Inner Sphere propaganda. I am NOT joking. From sarna.net:
>The animated series as such is not considered Canon for the BattleTech universe. Instead, the show canonically exists in-universe as a work of fiction: It has been referred to in-universe as a "popular but poorly reviewed holovid series" by Tharkad Broadcast Company, said to be loosely based on the exploits of the "real" First Somerset Strikers;[1][2][3] it was even known among Clan sibkos on the Clan Homeworlds by the 3070s through Solaris broadcasts.[4] The overall storyline and characters have thus been canonized at least in broad strokes.
In an attempt to reconcile as much content as possible from the show with the established canon of the BattleTech universe, FASA produced a fully canonical sourcebook that established the characters and (broadly) the events depicted in the show as real within the BattleTech universe. It introduced new technology and rules to account for items and events featured in the show, and addresses aspects of the show which appear to contradict established canon (including answering the question why Rhonda Snord was later attributed with having found Camelot Command first). Other conflicting information such as wrong uniforms, overly spacious vehicles and spaceships, and the odd selection of BattleMechs shown can be explained as inaccuracies of the show and artistic license.
Regarding the timeline, Era Report: 3052 clarifies that Somerset was indeed briefly retaken by the Somerset Strikers, but finding its position untenable, the AFFC ordered Adam Steiner and the Strikers to fall back to FedCom space instead of securing the world; it remained undefended and was captured again in the fifth wave of Clan attacks. The deportation of the world's population did not really take place. It is also explained that many of the more heroic events depicted in the show were actually taken from a second Somerset Strikers mission, against second-line Clan forces on Barcelona in 3052 with a substantially larger formation based around the Somerset Strikers.[3]