“The Eagles are coming! And many voices answered crying: The Eagles are coming! The Eagles are coming! The hosts of Mordor looked up and wondered what this sign might mean.
There came Gwaihir the Windlord, and Landroval his brother, greatest of all the Eagles of the North, mightiest of the descendants of old Thorondor, who built his eyries in the inaccessible peaks of the Encircling Mountains when Middle-earth was young. Behind them in long swift lines came all their vassals from the northern mountains, speeding on a gathering wind. Straight down upon the Nazgûl they bore, stooping suddenly out of the high airs, and the rush of their wide wings as they passed over was like a gale.”
Return of the King chapter 4.
“The Eagles are coming! And many voices answered crying: The Eagles are coming! The Eagles are coming! The hosts of Mordor looked up and wondered what this sign might mean. There came Gwaihir the Windlord, and Landroval his brother, greatest of all the Eagles of the North, mightiest of the descendants of old Thorondor, who built his eyries in the inaccessible peaks of the Encircling Mountains when Middle-earth was young. Behind them in long swift lines came all their vassals from the northern mountains, speeding on a gathering wind. Straight down upon the Nazgûl they bore, stooping suddenly out of the high airs, and the rush of their wide wings as they passed over was like a gale.”