thrice the people of feanor were driven back , and many were slain upon either side ; but the vanguard of the noldor were succoured by fingon with the foremost of the host of fingolfin , who coming up found a battle joined and their own kin falling , and rushed in before they knew rightly the cause of the quarrel ; some thought indeed that the teleri had sought to waylay the march of the noldor at the bidding of the valar .