The supply problems that Allies faced in Europe during World War II was that supplies had to travel a long distance across water on ships that were often attacked, so they did not reach Europe.
The Allies of World War II, known as the "United Nations" from the 1 January 1942 declaration, were the countries that together opposed the Axis powers during the Second World War. The Allies promoted the alliance in an attempt to control German, Japanese and Italian aggression.