Fighting began after supporters and opponents of deposed Egyptian President Mohamed Morsi of the Muslim Brotherhood took to the streets to commemorate the "Egyptian victory" in the Yom Kippur War, that broke out on October 6, 1973.Yeah, that was quite a victory -- the Egyptians regained the Sinai, and the Suez Canal (which had been closed for six years), dumped the USSR, made a peace treaty with Israel (which it has barely honored), and entered an unprecedented period of peace and (for Egypt and the non-OPEC muzzie world in general) prosperity. The fact is, that was Sadat's plan all along -- reestablish a line of control about ten miles east of the Canal, under a SAM umbrella, dig in, and make it too costly for Israel to retake it, forcing a negotiated settlement. Had the USSR known that Egypt had no plan to take the entire Sinai, it probably would still have kept the pot boiling. The Israeli strategy was to fight a slow retreat in the broad Sinai if need be, while dealing with the nearby Syrian threat. Egypt's and the USSR's Syrian "allies" might not have been mauled quite so badly if Egypt had not had that stop line, although it would still have been bad.
Wikipedia -- Egypt and Syria never disclosed official figures. The lowest casualty estimate is 8,000 (5,000 Egyptian and 3,000 Syrian) killed and 18,000 wounded. The highest estimate is 18,500 (15,000 Egyptian and 3,500 Syrian) killed. Most estimates lie somewhere in between the two, with the Insight Team of the London The Sunday Times combined Egyptian and Syrian losses of 16,000 killed, and yet another source citing a figure of some 15,000 dead and 35,000 wounded. U.S. estimates placed Egyptian casualties at 13,000. Iraq lost 278 killed and 898 wounded, while Jordan suffered 23 killed and 77 wounded. Some 8,372 Egyptians, 392 Syrians, 13 Iraqis and 6 Moroccans were taken prisoner. Arab tank losses amounted to 2,250 though Garwych cites a figure of 2,300. 400 of these fell into Israeli hands in good working order and were incorporated into Israeli service.The Syrian losses shown are probably far too low -- the Syrian army lost 1000 tanks, and it seems mighty unlikely that none of them had a crew inside. There's another section of the wiki page about Syrian and Egyptian atrocities against Israeli POWs, it's a little too disturbing to quote here.
Israel Defense Forces: Prisoner-of-War and Captive Soldier Exchanges -- During the Yom Kippur War (October 1973) 242 IDF soldiers were captured by the Egyptians, 68 by the Syrians, and 4 by the Lebanese. The IDF captured 8,372 Egyptians, 392 Syrians, 13 Iraqis, and six Moroccan soldiers. The prisoner exchanges with Egypt were held between 15 November 1973 and the 22 November 1973, during which POWs held by both sides since the War of Attrition were returned. On 4 April 1975, Egypt returned to Israel the bodies of 39 Israeli soldiers killed in action during the Yom Kippur War. In exchange, Israel returned 92 terrorists and security prisoners who had been held in Israeli prisons.
Thanks.