There is a word for a Government/military enforced wartime curfew.
Can't think of it! Auugh! People usually refer to the policy as "The
---------"  Someone will try to go outside, and the wife would say
"But honey!  The __________  ! "

"Blackout"

hmm.... not what I was thinking of... thanks, though!

Is it the Martial Law.

From wikipedia 
http://en.wikipedia.org/wiki/Martial_law

In many countries martial law imposes particular rules, one of which is curfew. 

Martial law is instituted most often when it becomes necessary to
favor the activity of military authorities and organizations, usually
for urgent unforeseen needs, and when the normal institutions of
justice either cannot function or could be deemed too slow or too weak
for the new situation; e.g., due to war.

Of course, its two words, not just one.

Nope!

This restriction or curefew was sometimes called "the precautions"

Air Raid Precautions
http://www.spartacus.schoolnet.co.uk/2WWarp.htm

Is that the term you're thinking of?

tutuzdad-ga