The Free Brotherhood was a band of space pirates, travelling the human-settled sectors of the Galaxy aboard huge hyper-capable transport ships, guarded by numerous light warships.
Although no match for standing military forces of developed star systems, the Free Brotherhood was strong enough to wreak havoc in a number of small, single-system star nations.
In 1433 PD, a first skirmish between the Free Brotherhood and the Manticore System Navy occured in the Megan System, after the Brotherhood's scouts had encountered two Manticoran frigates on a survey mission. During the following battle, one of the Manticoran ships was destroyed, allowing the other to escape and return home. The aroused Manticore proved to be a much tougher opponent that what the Brotherhood was used to, so the raiders eventually moved on towards the Haven Sector in search of easier prey. They raided and exploited Ramon, and a few years later raided the Zuckerman System. (Companion, MA1)
Some Redoubtable-class battlecruisers of the Royal Manticoran Navy saw action against the Free Brotherhood centuries later. (JIR1)