Thanksgiving was celebrated in America throughout the early 1800s, but it was a regional holiday, with states in the northeast observing it but often on different days. That all changed in 1863 when Abraham Lincoln, after some urging, issued a proclamation making Thanksgiving a national holiday.

The woman who convinced Lincoln to issue his Thanksgiving proclamation was Sarah J. Hale, the editor of a popular woman's magazine, Godey's Lady's Book. She had campaigned for years to make Thanksgiving a national holiday, and a letter she sent to Lincoln in September 1863 seems to have convinced him.

Lincoln, who was no doubt thinking of ways to unite the nation during the height of the Civil War, issued a proclamation in early October 1863 specifying that the last Thursday in November would be a national day to give thanks. Newspapers in the north printed the proclamation, and thus began the tradition of a national Thanksgiving holiday.

Image: Editor Sarah J. Hale, who urged Lincoln to issue a Thanksgiving proclamation/courtesy New York Public Library Digital Collections.

This week marks the 150th anniversary of the publication of On the Origin of Species, Charles Darwin's landmark treatise on evolution. In London bookshops on November 24, 1859 history was changed forever when curious people arrived to buy the new and startling book.

Charles Darwin had spent decades preparing to write his great work, amassing evidence in solitude as well as sailing around the world on a research vessel, H.M.S. Beagle. When the book finally appeared it sold out almost immediately and another edition was soon being printed.

On the Origin of Species generated countless controversies as, among other things, it contradicted the literal interpretation of the Biblical story of creation. Darwin remained mostly aloof from the firestorms, preferring to continue his research and writing.

Despite furious opposition to Darwin's ideas, his theories were vindicated. And when he died in 1882 he was hailed as a great scientist and was buried with state honors at Westminster Abbey.

Illustration: Charles Darwin/Library of Congress

Today marks the anniversary of one of the most quoted speeches in history, Abraham Lincoln's Gettysburg Address.

The speech was brief, and Lincoln only needed a few minutes to deliver it on November 19, 1863 during a ceremony to dedicate a military cemetery at the site of the Battle of Gettysburg.

At a time of great crisis, with the Civil War grinding on at enormous cost in human life, Lincoln desired an opportunity to make a statement about the war and its purpose. And when invited to speak at the event in Gettysburg, Lincoln crafted a profound text.

In less than 300 words, Lincoln gave a moral justification for the Civil War and presented his ideal image of an American government "of the people, by the people, for the people..."

The Gettysburg Address was distributed widely throughout the north, and it became an iconic statement of American purpose.

Photograph: Abraham Lincoln, portrait by Alexander Gardner, November 1863/Library of Congress

Stories of foreign troops battling in Afghanistan while diplomats try to find a strong leader for the remote and rugged country sound like today's headlines. Yet they perfectly describe Britain's war in Afghanistan in the late 1870s.

When the British invaded Afghanistan for the second time it wasn't to fight the Afghans so much as it was to thwart the Russian Empire. The feeling in London was that Russia wanted to eventually move southward and seize Britain's prize possession, India.

When the British Army marched into Afghanistan in late 1878 things actually went too well at first. A weak Afghan leader agreed to conditions he couldn't enforce, and the British soon faced a disaster in Kabul that could have rivaled the horrendous winter retreat from the Afghan capital in 1842.

After a year of both miscalculation and heroics, the result of the Second Anglo-Afghan War was that Britain installed an Afghan leader who would keep the country stable. And the Russians were denied a stepping-stone to the riches of British India.

Photograph: General Roberts, hero of Kandahar/Library of Congress