Eagle Warriors

Chapter Master: Gaius Aegius
Founding Chapter: Ultramarines
Successor Chapters: Unknown
Number: Unknown (Presumed ~1000)
Homeworld: None (Fleet-based)
Founding: Second Founding
Primarch: Roboute Gulliman (through Ultramarines)
Allegiance: Imperium of Man

Overview: A fleet-based chapter continually on campaign in the systems conquered by Robute Gulliman during the Great Crusade.

Notable Campaigns:

• The Eagle Warriors participated in the Balur Secundus Strike Force.
• The 4th company earned particular renown in the battle for Medusa V.
• A score of terminators participated in the Zeist campaign under the leadership of the Ultramarines.[2]

Sources:
1 Codex: Space Marines 5th Edition (2008). Ward, Matthew , Nottingham: Games Workshop.
a p.24
b p.48
2 Codex: Space Marines 3rd Edition (1998). pp. 22-23 Chambers, Andy , Nottingham: Games Workshop. (through warhammer40k wikia)

Pictures taken from warhammer40k wikia