Brandenburg Tor was once one of Known Space's most beautiful and vibrant worlds. However, Brandenburg has been off-limits to all Systems Commonwealth citizens since C.Y. 9766, the start of the Magog-Commonwealth War and subsequent Quarantine Zone. Approximately three billion died within five days. Brandenburg Tor now lies in territory ceded to the Magog by the Treaty of Antares. It is unknown whether the Magog use the planet as a breeding world, or have left it broken and deserted, a reminder of their first deadly contact with Commonwealth civilization. Brandenburg Tor remains a major center of Magog activity. It was well known for its "glittering city spires, its elegant orbital habitats, its soaring cloud forests, and its five million lakes." However, after the Battle of Brandenburg Tor,