Rearranging the letters of 'The great unknown' (Great mysteries) gives:
Unearth, get known.
(by Jim Banholzer) (2017) (pending approval)
Other related anagrams without their own page:
"Tomb of the Unknown Soldier, Arlington National Cemetery" -> "Bent on Memorial Day, we long for lost kin in that encounter." (by Adie Pena by hand) (2008) (pending approval)
"Battle casualties" -> "Let a blast cause it." (by Rick Rothstein using Anagram Genius) (2003)
"I know nothing!" -> "Thinking no ow!" (by Jim Banholzer) (2017) (pending approval)