Dash is one of those words with more meanings than letters. These include to rush (I dashed out), to destroy (my hopes were dashed), and a punctuation mark (em dash etc.). There are also various other meanings but those three are the most commonly used (as far as I know).
I can understand the link between the rapid action (to dash somewhere) and destruction, but am stumped trying to find a link between either and the "—". The online etymology dictionary is not very helpful here:
c.1300, probably from a Scandinavian source (compare Swedish daska, Danish daske "to beat, strike"), somehow imitative. The oldest sense is that in dash to pieces and dashed hopes. Intransitive meaning "move quickly" appeared c.1300, that of "to write hurriedly" is 1726. Related: Dashed; dashing.
late 14c., from dash (v.). Sporting sense is from 1881, originally "race run in one heat."
Neither of those touches on the punctuation mark. So, what is the etymology of dash ("-") and how is it connected, if indeed it is, to the other meanings of the word? Any comments on the various other meanings (such as He cut a dashing figure etc.) are also welcome.