(Image: Mike Licht)
Are you frustrated that you lost an hour today? That's nothing compared to the experience of daylight saving time during World War II. The belligerent nations often thought that adding extra daylight waking hours would increase productivity and decrease electricity expenditures. Winning the war necessitated maximizing this possible gain to the fullest advantage. Atlas Obscura describes their sometimes extreme efforts to alter official time.
In 1940, the United Kingdom added an hour in the spring. But the government decided to skip the fall reversal. Then, in the spring of 1941, it engaged in the regular adding of an hour. This was called Double Summertime.
In addition to the standard advantages of daylight saving time, Double Summertime made blackouts to prevent air bombings more effective because it gave workers time to get home before they went into effect.The UK decided to keep the practice for the rest of the war.
Other nations used time changes for administrative convenience. For example, Soviet-occupied Germany was on the same time as Moscow:
In 1945, Berlin and Soviet-occupied Germany went on Double Summertime for one summer, putting it in the same time zone as Moscow. Basically, time in Europe was extremely confusing for a while.