Earlier quoted context omitted.
Depends on the country: some have explicitly extended the copyrights for people who died in the war. For example, writers who died in active service of the French military have copyright for 100 rather than 70 years postmortem: http://en.wikipedia.org/wiki/Mort_pour_la_France
This makes a lot of sense. By extending copyright even further after their deaths, it will incent these authors to create more posthumous works!
Antoine de Saint-Exupéry is the only one on the list who I've heard of.