Imperial German plans for the invasion of the United Kingdom were first conceived in 1897 by Admiral Eduard von Knorr, commander of the Imperial German Navy, against a background of increasing Anglo-German rivalry and German naval expansion. Acknowledging the inferiority of the small German fleet, his concept called for a preemptive strike against the Royal Navy to establish temporary naval supremacy. This would be followed by an immediate landing, before British naval reinforcements re-established command of the sea. Subsequent studies determined that the shortest possible sea-crossing would be a prerequisite for success, requiring the use of port facilities seized in Belgium and the Netherlands to embark the expeditionary force. Reconnaissance of the English east coast was completed and potential landing sites in East Anglia were selected.
Comments were invited from Alfred von Schlieffen, Chief of the German General Staff, who regarded an invasion to be impractical. His staff estimated that it would require up to 320,000 troops to defeat the British home defences and capture London, and that a quick victory would be necessary if the expeditionary force was not to be cut off and forced to surrender. The plans were opposed throughout by Admiral Alfred von Tirpitz, State Secretary of the German Imperial Naval Office. They were shelved in 1899 when it became apparent that the German navy and merchant marine were not sufficiently strong to accomplish an invasion without compromising the secrecy considered essential for success. During the First World War, German naval operations against the British mainland were restricted to raids, designed to force the Royal Navy to dissipate its superior strength in coastal defence and thereby allow the smaller German navy to engage it on more favourable terms.