The 1541 Border Incident was a diplomatic crisis in which an Ardolon drone was discovered probing Bushrak territory and quickly shot down. The event ruined Ardolon-Bushrak relationships and completely dismantled the legacy they once held as the Zenith Powers.
After the Ardolons closed their borders to the Bushraks in 1540 CE, the Grand Alliance was nearly overflowing with tension. Everybody knew war was coming and the Ardolons suspected an incoming surprise Bushrak offensive as the Bushraks were known for absolutely disgusting tactics in time of war.
Naturally, they felt the need to probe their territory, but with the Bushraks possessing such advanced technology, they spotted the drone within the day. They immediately shot it down and accused the Ardolons of war crimes. From that point on, the galaxy waited in a cold war state, ultimately leading to the dissolution of the Grand Alliance.