Which ancient Gaelic warrior-poet was regarded by both Napoleon and Thomas Jefferson as surpassing Homer in greatness?

Explanation

Ossian is the legendary ancient Gaelic warrior-poet whom Napoleon and Thomas Jefferson admired, considering him greater than Homer. The other options refer to different figures: Macpherson was the collector who popularized Ossian's poems; Merlin is a mythical wizard; Decameron is a collection of tales by Boccaccio.