On 28 February 1904, Lieutenant Frank H. Schofield and two sailors aboard the USS Supply observed three bright red objects in formation.

The USS Supply observation matters because it is an early naval report of a red-object formation.
Documented
Three red objects were observed in formation
Debated
The identity of the objects
Unverified
Extraterrestrial origin
Sources are kept in separate layers: official and contemporary material is documented; secondary UFO literature is treated as debated, not as primary evidence.
Documented source.
Documented source.