Conversation so far:
What was Glenn Frey's tenure with the Eagles?
Glenn Frey and Henley decided to form a band together while on tour, joined by Meisner on bass and Leadon on guitar, banjo, steel guitar, mandolin and dobro, forming the Eagles.
What formed the Eagles band with Glenn Frey?
The Eagles began in early 1971, when Linda Ronstadt and her then-manager John Boylan recruited local musicians Glenn Frey and Don Henley for her band.
Who else joined the Eagles besides Glenn Frey and Don Henley?
It was later proposed that J. D. Souther should join the Eagles, but Meisner objected.
Did the Eagles Tour?
The Eagles toured consistently and were inducted into the Rock and Roll Hall of Fame in 1998.
What did Glenn Frey do after the tour?
The Eagles' album Long Road Out of Eden was released in 2007, and Glenn Frey participated in the Eagles' Long Road Out of Eden Tour.
How did the Eagles' album Long Road Out of Eden do when Glenn Frey participated?
The album Long Road Out of Eden became Glenn Frey's band the Eagles' sixth No. 1 album and was the highest selling album of the year.

Question: what was his greatest accomplishment?
Self-contained rewrite: What was Glenn Frey's greatest accomplishment?