A decisive First World War battle at Heligoland

Germany must attack before British reinforcements, minefields, and local defences make the fortress still harder to take. That urgency gathers German naval strength in one predictable place where the Royal Navy has friendly guns, local information, submarines, and a telegraph connection reporting the assault. The Grand Fleet can begin moving before the fortress falls and may arrive in less than a day once Germany is committed. Meanwhile, German ships consume ammunition and suffer damage bombarding the island, while British battlecruisers can threaten the Baltic behind them. The resulting action is forecast as a close slugging match into which Britain can throw pre-dreadnoughts, older destroyers, and every available reinforcement. Germany cannot gain much from a tactical withdrawal: failing to destroy the British force leaves the fortress intact and the surface fleet strategically trapped.