The Full Story
The Anglo-Portuguese alliance is the oldest in the world, dating to 1373. For nearly five centuries, Britain and Portugal had stood together through wars, invasions, and revolutions. But in 1839, that friendship nearly broke.
Portuguese ships were still carrying enslaved Africans to Brazil, which had been independent from Portugal since 1822. Despite treaties promising to stop, Portuguese slavers operated openly. Britain had had enough.
Lord Palmerston, the Foreign Secretary, pushed through legislation allowing the Royal Navy to seize Portuguese slave ships and try them in British courts. This was an extraordinary violation of sovereignty, treating an allied nation's vessels as pirates.
Portugal was outraged. Diplomatic relations nearly collapsed. There was talk of war. But Palmerston didn't back down. He made clear that Britain valued ending the slave trade more than it valued Portuguese friendship.
Faced with British naval power and diplomatic isolation, Portugal eventually complied. The slave trade from Portuguese Africa declined sharply. Britain had risked its oldest alliance and won.
Why This Matters
This shows Britain's priorities starkly. Nearly 500 years of alliance meant less than ending the slave trade. Palmerston was willing to risk war with a friend to free strangers.
Key Facts
- ⚠Correction: the video describes Brazil as a Portuguese colony in 1839; Brazil had been independent from Portugal since 1822. The alliance dates to 1373 (Treaty of Windsor 1386), closer to 470 years of friendship in 1839 than 600.