Conversation so far:
what silent films were made by gary cooper in 1925?
In early 1925, Cooper began his film career in silent pictures such as The Thundering Herd and Wild Horse Mesa with Jack Holt.
what other silent films?
Riders of the Purple Sage and The Lucky Horseshoe with Tom Mix, and The Trail Rider with Buck Jones.
did he win any awards for these films?
CANNOTANSWER.

Question: what was his greatest accomplishment?
Self-contained rewrite: What was Gary Cooper's greatest accomplishment?