You are right on Yvan...
According to
http://www.worldwidewords.org/articles/unpaired.htm, while discussing unpaired words, "...mantle and dismantle which came from the equivalent French verbs in about 1400 and 1580 respectively. (The early literal sense of dismantle was to remove one’s cloak or mantle, and hence to undress; it was later applied figuratively to the process of stripping a fortress of its defences; all these meanings existed in French before the word came into English. Here, mantle has not vanished, though it is rarer than its opposite.)"