The people of Gibraltar voted to remain British, and against unification with Spain, on this day, September 10th, 1967.

The result was overwhelming: 12,138 votes were cast to remain British. Just 44 people in all of Gibraltar voted to become Spanish.

Gibraltar has been under British rule since 1704, when it was captured by Anglo-Dutch forces in the war of the spanish succession, when the Hapsburgs claimed the vacant throne of Spain and were supported by the British against the French and Spanish. Although the Spanish won the war, and the Hapsburgs did not gain the throne, Britain managed to wrangle permanent sovereignty over Gibraltar in the peace treaty of Utrecht, in 1710.

Gibraltar has, ever since, been one of Britain’s most important strategic bases, because the Royal Navy, based there, could control entry and exit to the Mediterranean Sea from the Atlantic Ocean. This advantage helped Britain win the Napoleonic Wars, and gave it a huge naval advantage in the two world wars as well.

But Spain has always claimed the territory as rightfully Spanish. Though no war has ever been fought over it, tensions over sovereignty remain to this day. The 1967 vote was an attempt to demonstrate to the Spanish that Gibraltarian citizens have no desire for re-unification.

Thirty four thousand people live on Gibraltar today. It is almost entirely self-governing, and does not send representatives to the House of Commons. But Queen Elizabeth remains head of state.

And Spain, still, asserts its claim.