Harare - Here is a timeline of the political crisis in Zimbabwe, where Robert Mugabe resigned on Tuesday, following a military takeover and unprecedented mass protests that demanded that he steps down.Army takes controlNovember 14: Tanks are seen moving on the outskirts of the capital Harare - a day after army chief Constantino Chiwenga denounces Mugabe's sacking of vice president Emmerson Mnangagwa on November 6.Mnangagwa is seen as a rival of Mugabe's wife Grace, 52, to succeed the veteran 93-year-old leader.Later, heavy gunfire is heard near Mugabe's residence in Harare. Mugabe under house arrestNovember 15: By the early hours, military vehicles are on the capital's streets, but the army denies staging a coup, giving a televised address saying that Mugabe is safe and that they are "only targeting criminals around him".South Africa says Mugabe has told President Jacob Zuma by telephone that he is under house arrest but is "fine".The European Union and former colonial power Britain urge a peaceful resolution of the crisis, while South Africa warns against any "unconstitutional changes" of government.Mugabe refuses to resignNovember 16: Mugabe refuses to step down during talks with generals, a source close to the army leadership says, in a move which enrages many Zimbabweans who see it as a bid to "buy time" to negotiate a favourable end to his 37-year reign.A day later he appears at a university graduation ceremony, acting as if nothing happened.Opposition growsNovember 17: Eight out of the 10 branches of Mugabe's ruling Zanu-PF take to state television to demand that he stands down, in a call echoed by the influential war veterans association, which urges people to join huge street protests at the weekend. US Secretary of State Rex Tillerson says the people of Zimbabwe must choose their own government through elections.Mass protestsNovember 18: Tens of thousands of people flood Zimbabwe's streets demanding Mugabe's resignation in a joyful celebration of his apparently imminent demise.The display of open defiance would have been unthinkable just a week earlier.Mugabe hangs onNovember 19: Zanu-PF sacks Mugabe as leader and demands that he resign as head of state. It also expels his wife Grace and names ousted Mnangagwa as the new party chief.The ruling party also says Mugabe must resign as president by midday Monday, or face impeachment.But in a live televised address, Mugabe defies expectations that he will resign, instead saying he will preside over Zanu-PF's congress in December.Parliament starts impeachmentNovember 21: After the deadline passes without Mugabe resigning, Zimbabwe's parliament gathers to start the impeachment process, with lawmakers from across the spectrum calling on the president to quit. Mnangagwa calls for Mugabe to stand down in his first intervention since the army takeover, saying he should "heed this clarion call" so the country can move forward.Mugabe resignsAs MPs gather for a special joint session of parliament, speaker Jacob Mudenda reads out a letter from Mugabe resigning as president after a 37-year rule with immediate effect. "My decision to resign is voluntary on my part. It arises from my concern for the welfare of the people of Zimbabwe and my desire to ensure a smooth, peaceful and non-violent transfer of power that underpins national security, peace and stability."The bombshell announcement sparks scenes of wild celebration in the streets of Harare, with cars hooting and crowds dancing and cheering over the departure of the autocrat who has ruled Zimbabwe since independence.