What gentleman was portmanteau named after?

"Portmanteau" is not eponymous; that is, it is not derived from someone's name. Lewis Carroll coined a special use of the Word in Through the Looking Glass, And What Alice Found There. In that book, Humpty Dumpty explains the meaning of the poem "Jabberwocky" to Alice. When he gets to the Word "slithy," he says, "Well, 'slithy' means 'lithe and slimy'. 'Lithe' is the same Word as 'active'. You see, it's like a portmanteau -- there are two meanings packed into one Word." Why did Carroll choose portmanteau for "packing two meanings into one Word"? Because the original meaning of the Word is "suitcase."