The Second Succession War began in 2830 and lasted until 2864. It saw a significant reduction in technological advancement as the Successor Lords sought to cripple their enemies' ability to wage war. Instead, only a handful of planets changed hands and the interstellar civilization of the Inner Sphere had for the most part slipped to a level comparable in technological development to early 21st century Terra at its conclusion.
The First Succession War had seen significant atrocities committed by all parties and the cessation of hostilities was more from exhaustion than through any significant peace deals. During the nine years between the end of the First Succession War in 2821 and the beginning of the Second Succession War, the houses rebuilt their forces as rapidly as possible. Tensions remained high throughout the period, needing only a spark to set them ablaze.
Having built the religious transformation of ComStar around the prophecy of its rise to power after the Great Houses had destroyed themselves, Primus Conrad Toyama was increasingly dismayed by the relative peace. First using the ComStar News Bureau to sensationalize the damage of the minor raids that occurred such as the Chain Gang Missions, Toyama realized that he would have to more overtly force the matter, proposing Operation Divine Intervention to the Order's ruling First Circuit in early 2827.
At Toyama's direction, ROM began to filter information with regards the inner workings, composition and movements of both the Draconis Combine Mustered Soldiery and the Internal Security Force to agents of Loki, the Lyran Commonwealth's intelligence agency, while the ComStar News Bureau played up the extent of the raids and tension along the Free Worlds League and Lyran border. With the LCAF consistently outmaneuvering the Combine thanks to the leaked information, by 2830 an enraged Coordinator Jinjiro Kurita launched an all-out offensive against both Commonwealth and the Federated Suns to restore the honor of his troops, marking the formal start of the Second Succession War.
The First Succession War had been exceedingly brutal and horrific and the Second was no different. Hundreds of millions of civilians were slaughtered and technological and scientific facilities were again targeted by military forces. As more and more scientists and technicians were killed, several areas of advancements had begun to slip away almost entirely. As the war raged on, each house lost more and more of its capacity to wage war and make technological improvements.
Thanks to the brutal nature of the conflict and the efforts of ComStar's Operation Holy Shroud, by the end of the Second Succession War in 2863, the level of technological knowledge in the Inner Sphere had slipped drastically from its high point at the end of the Star League era around 2750. Several areas of knowledge and technological understanding had been lost, including vital technologies such as how to construct hyper pulse generators and the faster-than-light (FTL) Kearny-Fuchida Jump Drives used in JumpShips. The Great Houses' military forces were forced to cannibalize parts to effect repairs, rather than being able to manufacture replacements. People of the Inner Sphere knew how to use the technology, but they no longer understood how it functioned nor could they replicate its creation or manufacture. The technology was more akin to magic than science for most people. Only three years later, in 2867, the Inner Sphere would once again erupt in conflict; the low-intensity Third Succession War.