Reviewing the past, present, and future contribution of maritime forces to the conduct of expeditionary operations, the author concludes that the importance of this contribution is growing. He considers the diplomatic and "good order" roles of maritime forces which enable such operations in the first place. He reviews contemporary naval thinking about the nature and the relevance of sea control, and examines changes in the way maritime power may be projected ashore. Finally, the author analyses the extent to which future sea-basing can enable expeditionary forces can meet the challenges of the 21st century. Using past and recent experience, he demonstrates how important maritime outcomes are to the achievement and, equally important, the consolidation of victories ashore. Accordingly, navies around the world are having to adjust their plans and their priorities in order to meet these challenges.