A small Starfleet survey ship commanded by Una Chin-Riley on a first contact mission to Kiley 279 in 2259, whose three-person crew were seized by the planet's inhabitants.
The USS Archer was a small Starfleet vessel with a crew of only three. In 2259 it was sent to Kiley 279 under Lieutenant Commander Una Chin-Riley, first officer of the Enterprise, after a warp signature was detected there.
As shown in Strange New Worlds, the first episode of the series of that name, the signature was not a warp drive at all: the Kiley had built a weapon from technology they had observed during the battle near Xahea. Una and her two astrophysicists were taken prisoner, and the Archer was left empty in orbit.
Captain Pike cut short his leave and took the Enterprise to recover the crew. The ship was named after Jonathan Archer of the Enterprise NX-01.