Galdor saved the lives of Tuor and Ecthelion during the battle of Gondolin. Tuor, bearing the wounded Ecthelion, came to the Square of the Well. Here were Galdor and his elves defending the place and as Tuor came he stumbled beneath Ecthelion and fell and had it not been for the rush of Galdor coming to his aid, Tuor and Ecthelion would have been slain by the Orcs. Galdor escaped with the remaining refuges the fall of Gondolin and came to the Mouths of Sirion.
He survived the onslaught of the Sons of Fëanor and was rescued by Círdan and Gil-galad and sailed to the Isle of Balar. It might be that Galdor of the Tree is the same Galdor who was sent to Rivendell by Círdan from Lindon.