Here's why:
* Unexpected Assistance: The Eagles are a powerful race of birds that are known to be friendly to the people of Middle-earth, especially those who show them respect and kindness.
* Gandalf's Call: Gandalf, being a powerful wizard, has a connection to the Eagles. He calls upon them for help in a moment of dire need, recognizing their strength and potential to save the day.
* Goblins' Fear: The goblins are terrified of the Eagles, knowing they are superior in power and size. This fear allows the Eagles to easily dispatch the goblins and wargs.
The arrival of the Eagles is a dramatic and pivotal moment in the story, demonstrating the power of unexpected allies and the importance of maintaining relationships with those who can be of help in times of need.