Operation Neptune

During World War II, there were two operations named Neptune:

1. Operation Neptune referred to the initial phase of the Allied invasion of Normandy, Operation Overlord.

Although many references state that Operation Neptune refers to naval operations in support of Operation Overlord, the most reliable references make it clear that Overlord refers to the establishment of a large-scale lodgement in Normandy, and that Neptune refers to the landing phase; i.e. Neptune was the first part of Overlord. According to the D-day museum:

"The armed forces use codenames to refer to the planning and execution of specific military operations. Operation Overlord was the codename for the Allied invasion of north-west Europe. The assault phase of Operation Overlord was known as Operation Neptune. (...) Operation Neptune began on D-Day (6 June 1944) and ended on 30 June 1944. By this time, the Allies had established a firm foothold in Normandy. Operation Overlord also began on D-Day, and continued until Allied forces crossed the River Seine on 19 August 1944."

See also [1] for further support of this usage.

2. Neptun was the German counterattack by German ground forces against Soviet units near the Black Sea at Myschanko-Berg on 6 April, 1943. Part of the Battle of Stalingrad.

Operation Neptune is also a computer game produced by The Learning Company which was designed to teach children about basic mathematics. The gameplay had players control a submarine, called the Neptune, as it navigated through various parts of the ocean, while solving math problems in order to proceed, and picking up pieces of the "Galaxy space capsule" which crash-landed while being sent back to Earth from a team of astronauts and scientists on a top-secret research mission in deep space.