This stuff fascinates me. I believe I've already mentioned the amazing
Ghost Army, but if you haven't read about it yet, you really should.
And while you're at it, check out the entry on
Mulberry harbours.
P.S. And while we're at it, an interesting guy:
Washington Roebling. Who is connected to the above topics only by the tenuous threads of Wikipedia linkage (i.e. he suffered from caisson disease, and Mulberry harbours used caissons. Ah, the delights of Wikipedia-hopping).