A truce reached in 2152 between Vulcan and Andorian forces fighting over the planetoid the Andorians call Weytahn and the Vulcans Paan Mokar, brokered by Jonathan Archer.
Weytahn was a planetoid on the Vulcan-Andorian frontier that the Andorians had terraformed. Vulcan annexed it in 2097, removed the settlers and renamed it Paan Mokar, and a treaty of 2112 left it under Vulcan watch.
In the Enterprise episode Cease Fire, Andorian troops under Commander Shran occupy the abandoned colony and take hostages. Shran asks for Archer as mediator, to the displeasure of Ambassador Soval. Shran's lieutenant Tarah, who wants war, shoots down the shuttlepod bringing Archer, Soval and T'Pol to the talks.
Archer exposes her and brings Shran and Soval to the table. A ceasefire is agreed, and both sides accept that humans may be useful as go-betweens, an early step towards the later alliance.