What would "Peace Through Strength" be in Latin?  I have looked up the
words seperately in a couple of online dictionaries and come up with
"Pacis Perductum Vis".  Since it's been many years since I had to do
anything in Latin, I'm pretty sure that my translation is wrong. 
Thanks for any help.

Dear wildsoul

Thank you for your question. I think your translation might mean
"Strength Through Peace". A Latin translation of "Peace Through
Strength" is "Pax propter vim".

It is the motto of the USS Dewey: see "USS Dewey DLG-14 Ships Crest"

http://www.angelfire.com/ca2/gormady/page4.html

where the Latin is translated as "Peace through Power".
I hope this is useful - please ask for a clarification if you require further help.
Kind regards

blackbird-ga

============
search strategy:
personal knowledge; Latin dictionary
Google search on "pax * vim"

Great answer.  Thank you!

A friend of mine (who's as "fluent" in Latin as anyone I know)
suggests "per potestatem pax" and comments "that way you get some
groovy alliteration too".

- Librariankt

One could also use the ablative of means, cum + ablative, cum vi(ri) pax.
Or cum robore pax, robur, roboris - strength (from oak), if one were
looking for the sense of enduring strength, rather than active force.

hlabadie-ga

I should have added this in my rating.

 "Peace Through Strength" is now the motto of the USS Ronald Reagan (CVN-76) also.