Israel recently marked the 50th anniversary of the 1973 war that began on Oct. 6, 1973.

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The Yom Kippur War

It was a surprise attack by Syrian tank columns and Egyptian brigades, according to Reuters. It caught the Israeli military off guard as they were starting to observe Yom Kippur, which is the the holiest day in Judaism.

Prime Minister Benjamin Netanyahu and former Labour Party premier Ehud Barak both fought in the Yom Kippur War and helped to establish what they believed was necessary to protect Israel, Reuters reported.

A total of 2,656 Israeli soldiers were killed in the war and 7,251 were injured, according to The Jerusalem Post. There were 294 prisoners of war. Casualties on the other side had no exact number, Reuters reported. It was estimated to be around 15,000 Eqyptians killed and 3,500 Syrians killed.

Five years after the war, Israel and Egypt signed a peace deal. It was the first peace deal with an Arab country, Reuters reported. Another peace treaty was then signed with Jordan in 1994.

What is Yom Kippur?

Yom Kippur in the Jewish religion means “Day of Atonement,” and is one of the holiest days of the year. Those who observe fast the entire day. The day, according to Chabad, is spent in the synagogue where those pray for forgiveness.

The holiday is about two calendar days as the Jewish calendar is lunar, according to CNN. Lunar means sunset to sunset. This year’s holiday started at sunset on Sept. 24 and continued through the night of Sept. 25.

Yom Kippur starts with the Jewish New Year which is called Rosh Hashanah, CNN reported.

“Jews around the world are to face their misdeeds and sins over the year through worship and prayer so that they may atone for their wrongdoings. With fear and wonder in facing God’s judgment, Jews seek forgiveness. In doing so, people are called to self-reflect on their failings and flaws,” CNN reported.