The deadly crackdown on the pro-Morsi demonstrations in Cairo comes after more than a month of failed negotiations and several violent attacks on protesters.
The main sit-in, outside a mosque in Cairo's Nasr City neighbourhood, started on June 28, days before the anti-government protests which led to Morsi's overthrow.
Protesters said they wanted to "defend Morsi's legitimacy."
It continued through the July 3 coup.
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Just hours after the army deposed Morsi, protesters pledged to continue their sit-in until he was reinstated. And they did, through the Ramadan fast and the Eid al-Fitr holiday, until security forces made their move on Wednesday morning.
The move to clear the sit-in is the third major assault by security forces.
The first came on July 8, when the army attacked protesters camped outside the Republican Guard headquarters, just north of the mosque.
More than 50 people were killed, many of them in the middle of their dawn prayers, according to witnesses and autopsy reports.
Dozens more were killed on July 26, when security forces attacked protesters who tried to extend their sit-in onto a major highway in Nasr City.
The shootings came hours after a massive pro-military rally called by the army chief, General Abdel Fattah el-Sisi.
Weeks of failed talks
Amid the violence, representatives from Egypt's political factions had been meeting to look for a peaceful resolution.
Senior Muslim Brotherhood officials deny that they have spoken directly with the army.
Instead, sources say that the two sides have communiated through intermediaries, including former presidential candidate Mohamed Selim al-Awa and liberal politician Amr Hamzawy.
Awa's initiative would have seen Morsi and the constitution briefly reinstated; the president would then hand his powers to an interim cabinet, before early elections within two months.
His proposal could have satisfied the Brotherhood, which has hinted in interviews that it would accept Morsi's ouster if the 2012 constitution was restored.
"Maybe he's back for one minute. And we have some sort of agreement that he's back and the first decision is to resign. Fine," Amr Darrag, a senior Brotherhood official, said in an interview last month.
But the army showed no willingness to reinstate Morsi, however briefly.
The most prominent major attempt at mediation came earlier this month, when international envoys from the US, the EU, Qatar and the UAE tried to defuse the crisis.
String of visitors
Catherine Ashton, the EU foreign policy chief, was allowed to visit Morsi in detention.
She said he seemed well, but offered few details of their conversation.
Several diplomats, including US Deputy Secretary of State William Burns, met Khairat al-Shater, the Muslim Brotherhood's jailed strategist and the man considered by many Egyptians to be the real power behind Morsi].
It was never clear how much progress they made bridging the gaps between the Brotherhood and the interim government. And their work was upstaged somewhat by two US senators, John McCain and Lindsey Graham, who flew to Cairo last week for their own meetings.
In a press conference shortly before they left, McCain repeatedly called Morsi's removal a coup.
"If it walks like a duck, and it quacks like a duck, it's a duck," he said.
Ahmed al-Muslemany, Egypt's presidential spokesman, called McCain's remarks "moronic" and hours later the presidency announced that foreign mediation efforts had failed.
Egypt's highest Islamic authority, Al-Azhar, tried to broker its own reconciliation meeting this week, amid growing rumours of an impending crackdown on the sit-ins.
Interviews with cabinet members and other politicians suggested the government was divided.
The army and police, along with many ministers, wanted to move quickly to disperse the protests, but were opposed by a handful of leading liberal figures, including Mohamed ElBaradei, the deputy president, and Hazem el-Beblawy, the prime minister.
Sources say that ElBaradei may resign in the coming hours in protest against the army's crackdown.
Nonetheless, some of his political allies have already come out in support of the security forces: a spokesman for his National Salvation Front, which was the main opposition bloc during Morsi's tenure, endorsed their action.
"These sit-ins, which are not peaceful at all, have been around for nearly 48 days, blocking main roads," Khaled Daoud told Al Jazeera.
"We've been living in a standstill for the past 48 days."
In a statement issued on Wednesday, the interim cabinet praised the security forces for their "self-control" and blamed the Muslim Brotherhood for the violence.