First Kinslaying at Alqualondë

When Fëanor decided to leave Valinor he needed ships to travel to Middle-earth, but the Noldor possessed no ships, and Fëanor feared that any delay in their departure would cause the Noldor to reconsider. Feanor approached the Teleri elves for help and the Teleri (under the leadership of Olwe) refused; stating that this was not the will of the Valar. In a rage, Feanor ordered his troops to take the ships by force and a battle broke out.

Then the Noldor drew swords, and the Teleri their bows, and there was a bitter fight that seemed evenly matched, until the second Host of the Noldor, led by Fingon, arrived together with some of Fingolfin's people. Misunderstanding the situation, they assumed the Teleri had attacked the Noldor, and they joined the fight. In the end, many Teleri were slain and the ships were taken.