What changed this was the Thirty Years War in Europe in the 17th century.

WSJ: The Weekend Interview with Charles Hill: The Empire Strikes Back

And yet during the period of the Thirty Years War (1618-1648) Elizabeth was one of the foremost power brokers for the Protestant cause in Europe.

BBC: A Point of View: The Winter Queen of Bohemia

The court of Louis XIV was impressed as much by the neckerchiefs of Croat mercenaries employed to fight the Thirty Years War as by their fighting spirit.

ECONOMIST: Men's clothing

As a proportion of the population, more people were killed during the An Lushan rebellion in eighth-century China, for example, or by the Thirty Years War in 17th-century central Europe.

ECONOMIST: The second world war

In 1632, Sweden's King Gustavus II was killed during the Battle of Lutzen in the Thirty Years' War.

CNN: Thursday,

In 1675, Henri de Turenne, French military leader in the Thirty Years' War, was killed during the Battle of Sasbach during the Dutch War.

CNN: Monday,

For thirty years, after the second world war Labour Governments thought their job was to manage an inevitable economic decline.

BBC: NEWS | UK | UK Politics | David Davis speech in full

There is something surreal about the way in which the Vietnam War has become a central preoccupation of a presidential campaign being waged thirty years after it was lost.

CENTERFORSECURITYPOLICY: Kerry's bait-and-switch

After Gertrude's death, the dynasty she had put in place continued for thirty-two more years, while Europe plunged into war again after only thirteen, dragging the rest of the world with it.

NPR: Excerpt: 'Gertrude Bell'

Yet a mere thirty years after the end of the Franco-Prussian War, when the smallpox epidemic swept through the United States, a whole host of intelligent people refused to be vaccinated, convinced that the vaccine did more harm than good.

FORBES: When Americans Rejected Small Pox Vaccines