I thought the character "を" (wo) was only used for the particle whose only job was to indicate the direct object of a verb.
But today I saw it at the end of an exclamation on a sign I think on a shop:
So what job is を doing here?
It's still the object marker. The sentence is just not finished and the verb is implied.
(there was a question mentioning suspended sentences but I cannot find it for the moment)
Anyway it's often used:
May the force be with you!
Additionally it gives some kind of propaganda feeling to the sentence.