beachhead

noun

1. the area that is the first objective of a military force landing on an enemy shore.
2. a secure initial position that has been gained and can be used for further advancement; foothold: The company has won a beachhead in the personal computer market.

noun military

1. an area on a beach that has been captured from the enemy and on which troops and equipment are landed
2. the object of an amphibious operation

n.

1940, in reference to German military tactics in World War II, from beach (n.) + head (n.), on the model of bridgehead, but the image doesn’t quite work.