Both blockades starved civilians to force a government’s hand. Is there a defensible moral line between the British blockade and the U-boat campaign?

THE SHORT ANSWER

• Why Germany built a fleet it couldn’t use. Tirpitz’s “risk fleet” was meant to be dangerous enough that Britain would concede colonies and neutrality rather than fight. It achieved the opposite: it identified Germany as Britain’s existential rival, drove Britain into ententes with France and Russia, and then — too small to win, too precious to lose — spent the war at anchor while its idle crews incubated the mutiny of 1918 (Ch. 11). A procurement decision as a first cause of the war’s alignments: navies are diplomacy in steel.
• The blockade’s legal fiction. Britain stretched “contraband” to cover food and stopped neutral ships wholesale, paying in American irritation but cash-settling claims; distance made it bloodless to watch. The U-boat could not stop and search — its only weapon was sinking. The two blockades killed by the same logic (cut the enemy’s inputs), but one drowned neutrals visibly. The Lusitania’s 1,198 dead (marked here) did more to define “Hun barbarism” in American eyes than three years of the hunger blockade did in any direction — a study in how morality tracks visibility.
• Holtzendorff’s spreadsheet. The 1917 decision was made against the Chancellor’s judgment, on a staff study: X tons sunk, Y neutral tonnage frightened off, Britain’s grain reserve Z weeks — therefore victory in five months, “before a single American soldier sets foot on the continent.” Every input was individually defensible; the model just omitted the enemy’s countermoves (convoy, rationing, American shipyards). It is the war’s purest case of quantified wishful thinking — precision mistaken for truth.
• Why convoy waited three years. The Admiralty resisted convoy with reasons that sounded technical — merchant skippers can’t keep station, ports will congest, escorts are “defensive” — and were really doctrinal: the navy of Nelson hunted enemies, it did not shepherd freighters. The fix required outsiders’ statistics (junior officers and a civilian ministry showed the “weekly 5,000 sailings” figure was inflated 20-fold) and prime-ministerial pressure. Institutions defend their self-image longer than their interests; the sea war’s decisive innovation was a management decision.

WHAT IT CHANGED

America in. Unrestricted sinking plus the Zimmermann telegram (Berlin inviting Mexico to attack the United States — intercepted by British codebreakers and gleefully published) ends American neutrality on 6 April 1917. What it changes first is not soldiers but solvency: the Entente was nearly out of dollars and credit; now the loans, steel, wheat and shipping are unlimited. The soldiers — two million by late 1918 — are the second installment.

The hunger that outlasted the guns. The blockade continued after the armistice, through the winter of 1918–19, as leverage on the Versailles signature. German memory fused “hunger blockade” and “dictated peace” into one grievance; the next German regime planned autarky and conquest of grain lands explicitly against a repeat. Weapons aimed at civilians teach civilian lessons.

A rulebook written in wrecks. Prize law, submarine ethics, the targeting of food — the sea war of 1914–18 posed every question the next century’s total wars would answer worse. Note for the exam of history: in 1939–45 every navy, including the democracies’, adopted unrestricted submarine warfare from day one. What 1917 made scandalous, 1941 made standard.