I'm working on some webpage fiction. Part of this requires a Latin
motto for a fictitious country. The phrase I need translated into
Latin, as closely as possible, is: "Onward, for King and Country", or
"Onward! For King and Country", with the latter being the preferred
version I had in mind.

Hello.

I'd go with:

"Prorsum! Pro rege et patria."


Sources:

"prorsum" = "onward" or "onwards"
://www.google.com/search?hl=en&lr=&q=+prorsum+%28onwards+OR+onward%29&btnG=Search

"pro rege et patria" = "for king and country"
://www.google.com/search?hl=en&lr=&q=%22pro+rege+et+patria%22+%22king+and+country&btnG=Search

------------
search strategy:
My own knowledge of Latin, plus various searches:
latin "for onwards" etc

I hope this helps.

The answer and comments have given me the information I needed without
fuss. Well done to all.

I reccomend William Whitaker's Words -
http://catholic.archives.nd.edu/cgi-bin/words.exe - if you need a
quick latin-to-english word translator.

Prorsum is an adjective. I'd think you need an imperative verb, but
I'm at a loss on that.



Centurion: Romanis eunt domus? People called Romanis they go the house?

Brian: It says, "Romans go home!"

Centurion: No it doesn't.

Markvmd's assertion that prorsum is an adjective is incorrect.

Prorsum is an adverb.
://www.google.com/search?hl=en&lr=&q=Prorsum+adv&btnG=Search

It is acceptable to use an adverb by itself as a motto. Indeed, as
indicated above, "prorsum" is used as a motto by various ships.
://www.google.com/search?hl=en&lr=&q=+prorsum+%28onwards+OR+onward%29&btnG=Search

I am sorry, Juggler. You are very much correct and I apologize humbly
and profusely. What I meant to say was "onward" is an adjective
(though it takes an adverb form as well) and was wondering if this was
the right word. Your citations show that it is.

Puh-leez, tell me you family motto isn't "Nemo me impune lacessit."