In 1869 the Suez Canal opened under Napoleon III, linking the Mediterranean with the Indian Ocean. Initially the Canal was opposed by the British; but once opened, its strategic value was quickly recognised and became the "jugular vein of the Empire". In 1875, the Conservative government of Benjamin Disraeli bought the indebted Egyptian ruler Isma'il Pasha's 44 percent shareholding in the Suez Canal for £4 million (£340 million in 2013). Although this did not grant outright control of the strategic waterway, it did give Britain leverage. Joint Anglo-French financial control over Egypt ended in outright British occupation in 1882. The French were still majority shareholders and attempted to weaken the British position, but a compromise was reached with the 1888 Convention of Constantinople, which made the Canal officially neutral territory.
The Suez Canal became neutral territory by what treaty?
Convention of Constantinople