A Commonwealth Timeline
9766 CY: The mixed human/Perseid/Nietzschean world of Brandenburg Tor is attacked by a previously unknown species. All but a handful of the planet's three billion sentients are killed by the mysterious attackers, whom the terrified survivors dub the Magog. Fifteen years of sporadic Magog incursions and attacks follow, though none as devastating as the first. The disbandment referendum is postponed indefinitely.
9781 CY: Commonwealth diplomats negotiate the Treaty of Antares, officially suspending hostilities with the Magog. The non-aggression treaty is signed over the vigorous protests of Nietzschean representatives, who back a campaign of total extermination against the Magog. Fifteen Nietzschean worlds threaten complete secession from the Commonwealth, but eventually back down after security assurances are given by High Guard command.