How did the British maintain an effective blockade of Germany in WWI? The distant blockade required vast resources. The policy of blockading neutrals and other unlawful matters aroused international consternation and required public relations campaigns of great depth.
The policy of buying cargos declared contraband at market rates was ruinous. The policy of buying out commodity markets to prevent other powers purchasing, for example nitrates, was also ruinous. The UK became a compulsory purchaser of last resort for at least 55% of Germany’s former imports, effectively 10% of pre-war German GDP,(wiki, archives) and that this would be necessarily purchased via gold backing or on credit dependent on the primary neutral which the blockade incensed. The composition of these purchases were not dictated by the UK’s war needs, but by Germany’s former trade arrangements.
How did the UK manage to piece together these policies, keep them effective, and avoid the wroth of major mercantile and trading neutrals such as the US over its illegal blockade?
Sources: - https://en.m.wikipedia.org/wiki/Blockade_of_Germany - http://www.nationalarchives.gov.uk/pathways/firstworldwar/spotlights/blockade.htm
The Wikipedia article lacks much on the “How” of the mechanics and is entirely deficient on the institutional and economic capacities of the UK to develop and implement these policies.