A statue of Winston Churchill stands outside the British Embassy in Washington. (Jahi Chikwendiu/The Washington Post)

Winston Churchill shivered as he stood in the South Portico of the White House at twilight on Christmas Eve in 1941.

It was less than three weeks after the Japanese attack on Pearl Harbor, and the visiting British prime minister had joined President Franklin D. Roosevelt to light the national Christmas tree on the South Lawn.

“This is a strange Christmas Eve,” Churchill told a quiet crowd of about 30,000 people. “Almost the whole world is locked in deadly struggle, and with the most terrible weapons which science can devise.”

But here he felt at home. “I cannot feel myself a stranger,” he said. “I have a right to sit at your fireside and share your Christmas joys.”

This week, Washington is marking its ties to the legendary statesman who led Britain through World War II with a Churchill conference and the opening of a new Churchill center and library at George Washington University.

Lbrarians sort the archive of Winston Churchill's appointment books at the National Churchill Library and Center at George Washington University, which officially opens Saturday. (Jahi Chikwendiu/The Washington Post)

The 33rd International Churchill Conference began Thursday and runs through Saturday at the Mayflower Hotel, and the National Churchill Library and Center opens Saturday.

Churchill, whose mother was American, visited Washington 13 times between 1900, when he was 26, and 1959, according to Christopher H. Sterling, an emeritus professor of media and public affairs at George Washington.

He went to church here, met presidents and may have had a mild heart attack trying to open a window in the White House in 1941.

He slept late, stayed up late and filled the executive mansion with cigar smoke, Sterling said.

Churchill is also said to have been seen naked in the White House after taking a bath, when Roosevelt blundered unannounced into his room.

And Churchill’s Washington speeches were legendary.

The day after Christmas in 1941, less than a month after the United States entered World War II, Churchill, wearing his trademark bow tie and round-rimmed glasses, addressed Congress.

Britain had already been at war with Nazi Germany and its allies for 2½ years.

“Here in Washington, in these memorable days, I have found an Olympian fortitude,” he told those assembled in the Senate chamber. “Here we are together, facing a group of mighty foes who seek our ruin. Here we are together defending all that to free men is dear.

“It is not given to us to peer into the mysteries of the future,” he said. But he was sure that “in the days to come, the British and American peoples will . . . walk together in majesty, in justice and in peace.”

The legislators rose and cheered, according to a newspaper account at the time. The prime minister flashed a V for victory sign with his right hand and waded into a delighted crowd of bystanders waiting outside.

The Churchill center at George Washington is housed in the university’s Gelman Library and is envisioned as a place of Churchill scholarship and a resource for the university.

It is the result of a partnership between the school and the International Churchill Society, a membership organization that raised the $2.5 million for the center, said Michael F. Bishop, the center’s director.

This year, the society gave the center a collection of Churchill’s yellowed engagement cards that were kept when he was in office. The brief entries, often written by Churchill’s secretaries, record meetings with royalty, scheduled speeches and briefings on the war.

A Nov. 13, 1942, entry notes an “anti U-boat meeting,” a reference to the menace of German submarines. Other entries say simply, “dentist,” or “cinema.”

“This is a really fascinating, contemporary record of Winston Churchill’s day-to-day activities as prime minister during the Second World War,” Bishop said. “This is the largest collection of these . . . anywhere.”

The cards were probably saved by one of Churchill’s private secretaries after the war, said associate university librarian Elisabeth Kaplan. The university has 30 of them.

They eventually became part of the collection of publisher Steve Forbes, who gave them to the Churchill society, which then gave to the university, Kaplan said.

The cards are online, and most have been transcribed, she said.

Bishop said: “They have been in private hands for a long time, and no one has had access to them. Now, here, visitors can come. They can request the originals, and take a look.”

Churchill’s ties to Washington were largely connected to his urgent need to have the United States join the Allied side during the war.

“When he heard about Pearl Harbor, while he was horrified by what happened. He said that night he slept the sleep of the saved and the thankful,” Bishop said. “He knew that would change everything.”

After the Dec. 7, 1941, attack, which plunged the United States into the war, Churchill immediately made plans to go to Washington and see Roosevelt.

It was during that visit that he addressed Congress and helped light the national Christmas tree.

It was also during that visit Roosevelt apparently saw the British prime minister in the buff.

“It’s one of those stories that I pray is really true,” Bishop said. Churchill, fresh from a bath, lost his towel just as Roosevelt entered his room.

“Churchill turns to Roosevelt and says . . . ‘The prime minister of Great Britain has nothing to hide from the president of the United States,’  ” Bishop said.

It was in the same bedroom after addressing Congress in 1941 that Churchill had brief chest pains, his doctor, Charles Wilson, wrote years later.

Churchill summoned Wilson the next morning and described the symptoms. Wilson wrote later that they were “those of coronary insufficiency,” if not an actual heart attack.

But he decided not to tell Churchill, because of his importance on the world stage at that moment.

The prime minister went on to live another 23 years.