The D'Vahl was a Vulcan ship that came to Earth to retrieve the survivors of a survey vessel which had crashed near Carbon Creek, Pennsylvania, in 1957.
The D'Vahl features in the Enterprise episode Carbon Creek, in the story T'Pol tells Archer and Tucker about her second foremother, T'Mir. T'Mir's survey ship crashes in Pennsylvania while observing the launch of Sputnik, and the three survivors live for months among the people of a small mining town.
They assume that their distress signal was never received. In fact a Tellarite freighter picked it up and passed it on to the High Command, and the D'Vahl is sent to collect them.
By then Mestral has decided he wants to stay and study humanity. T'Mir and Stron tell the rescuers that he died in the crash, and the D'Vahl leaves without him.