French submarines were built for wider work than the Mediterranean alone required. Long range was more obviously useful to an Austro-Hungarian boat trying to escape the Adriatic than to a French boat entering it. France was also considering how to assist Britain in the North Sea. Submarines positioned near German ports could observe movements and reinforce the information collected by British listening stations. A distant blockade still needs an inshore element close enough to see what an opponent is doing, even when the main battle fleet stays far away.
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Submarines behind a distant blockade
Long-range submarines could support a distant blockade by watching ports and extending the intelligence picture beyond shore-based listening stations.