[Thinkin' Gal]

The Germanic word for the dative case, der Wemfall, reflects the der-to-dem change. The question word in the dative is, naturally enough, wem ([to] whom): Wem hast du das Buch gegeben?, Whom did you give book? (Who'd you give the book to?)

http://german.about.com/library/blcase_dat.htm

[Erasmus]

Now, Thinkin', that's muddying the waters with the indirect objective case, which maps completely onto the objective case in English, but not in German. (i.e., Dative <> Accusative).

[aculeus]

Whom cares?