Third Hidden War
After the formation of the Star League and its mammoth Star League Defense Force, the ever present scourge of piracy greatly declined in the wake of Reunification War. Unfortunately the weakness revealed by First Lord Jonathan Cameron's inaction during the so-called Second Hidden War lead to an worrying upswing in bandit raids along the border worlds of the Inner Sphere, adding to the increasing tension and malaise of the era.
The situation escalated in 2741 when a group of bandits raided the Lyran Commonwealth world of The Edge. Armed with a battalion's worth of brand new BattleMechs, the bandits destroyed everything standing between their LZ and their objective, a rare metals refinery and its stockpile in the centre of the planet's capital. The local garrison were no match for the bandit's cutting-edge hardware and more than five hundred Lyran civilians died in the raid. Appalled, Archon Michael Steiner offered a huge reward for any information about the raiders' whereabouts.     
With aid from the Terran Hegemony and information provided by an anonymous free trader, the Lyran Intelligence Corps successfully located the bandits' base on the Rim Worlds Republic planet of Butte Hold the following year, with the 12th Lyran Regulars dispatched after them. Eager to avenge those killed on The Edge, the Twelfth caught the bandits unaware and easily captured or killed them in the desolate planet's desert plains. Interrogating the few surviving bandits almost to the point of torture, the LIC discovered the startling news that the bandits were in fact mercenaries employed and equipped by the Draconis Combine, who had styled them as pirates to avoid implicating the Combine with orders to specifically target certain Lyran worlds.    
At the winter Council session of 2742, Archon Steiner angrily confronted Coordinator Takiro Kurita with irrefutable proof of the mercenaries’ origin. Takiro simply laughed at the Archon, initially claiming that Steiner had falsified the evidence but eventually stating the Lyrans of all people knew that "business was business". Enraged by his response, Michael Steiner leapt at the Coordinator, wrestling him to the floor and landing several blows before the Council Guards could physically separate them. Both parties demanded the First Lord Simon Cameron intercede on their behalf but Cameron prevaricated and a furious Steiner threatened war. 
By January 2743 five brigades of Commonwealth troops massed on the Combine border, forcing the Combine to respond in kind and putting both realms on a war footing. Unlike his father's reluctance to involve the Star League in the War of Davion Succession, Simon did not tolerate the House Lords' posturing and in March of that year sent in a large number of SLDF troops and WarShips to the region, the show of force cowing both the Lyran and Kurita forces to stand down by mid-year. Despite backing down from full-on warfare, the tempo of the "bandit" raids continued to grow rapidly as all the Council Lords began to use such disguised forces to settle their grudges and grievances.  
With the Council Lords all publicly denying any knowledge or responsibility for these "renegades", even when confronted with blatant evidence of their duplicity gathered by Star League Intelligence Corps, the First Lord put aside diplomacy and ordered the SLDF to shoot on sight any unmarked and unresponsive soldier, vehicle or ship. Incensed at Cameron's interference, soon disguised House WarShips began escorting the "bandits" and protecting them from SLDF assault. When challenged by the First Lord on this new escalation, the House Lords either made hollow claims of "bandit"s capturing their vessels or blaming internal opponents having gone rogue.  
With the Council Lords refusing to put aside their differences and barely acknowledging his authority, in response to the increasing threat to the continued unity of the Star League, First Lord Cameron decided to appeal directly to its people, launching his famed Grand Tour that ended abruptly with his death at Star's End.   
While the "bandits" would continue to launch raids, the Third War largely concluded in 2752 as the death of Simon Cameron and the regency of General Aleksandr Kerensky gave the Council Lords far more free room to push their agendas in a more open fashion. The Council Lords' amendment to the Cameron Act of 2650, doubling the allowed size of the House militaries, also enabled them to integrate many of the "bandit" forces they had disavowed into their formal armed forces. 
- Era Report: 2750, p. 34 "History and Review - Chaos - Third War"
- The Star League, pp. 65-66 "History - Peace and Prosperity - Enemies Once More"
- Historical: Liberation of Terra: Volume 1, p. 20 "Rise and Fall of the Star League - Decline and Fall - Star's End"
- Handbook: House Steiner, p. 30 "Golden Age - The Slow Fall"
- House Steiner (The Lyran Commonwealth), p. 38 "History - The Star League Era - The Good Years - Steiners Triumphant"
- The Star League, pp. 65-66 "History - Peace and Prosperity - Peace Mission, 2750"
- Era Report: 2750
- Handbook: House Steiner
- Historical: Liberation of Terra Volume 1
- House Steiner (The Lyran Commonwealth)
- The Star League