Frontier Day

Frontier Day was a Federation holiday that commemorated the anniversary of the Enterprise NX-01's maiden voyage in April of 2151.

250th celebration

For the 250th Frontier Day in 2401, Admiral Jean-Luc Picard and Captain William T. Riker were due to speak, and the USS Enterprise, NCC-1701-F was slated for early decommissioning.

Ahead of the day, a recruitment drive was held, for which a statue of Enterprise-C's Captain Rachel Garrett was to be dedicated.

Unfortunately, this was the day the Borg chose to commence their plan of assimilating the entire Federation at once. Under the influence of Changeling infiltrators, preparations for the all-day celebrations were classified at the highest level, which involved the unprecedented gathering of the entire Federation fleet at Earth for display exercises. After giving a speech, Admiral Elizabeth Shelby ordered a demonstration of fleet formation mode, which caused the entire fleet to be enslaved to a Borg-altered automated network. With the ships inter-connected, 339 starships were started to undergo assimilation by way of a "back door" virus that assimilated by working with the transporter systems.

Before the Borg could destroy Earth, Jean-Luc Picard and his newly-acquainted, partially-assimilated son managed to destroy the Borg cube from the inside. With the Borg's biggest faction -and its Queen- destroyed, the previously-assimilated Starfleet officers were freed.