The state remained neutral throughout World War II (see Irish neutrality), which saved it from much of the horrors of the war, although tens of thousands volunteered to serve in the British forces. Ireland was also impacted by food rationing, and coal shortages; peat production became a priority during this time. Though nominally neutral, recent studies have suggested a far greater level of involvement by the South with the Allies than was realised, with D Day's date set on the basis of secret weather information on Atlantic storms supplied by Ireland.