Iran began six days of funeral ceremonies Saturday for slain Supreme Leader Ali Khamenei, with thousands of mourners filling Tehran's Grand Mosalla in scenes Iranian authorities hope will serve as a show of strength to the Islamic Republic's adversaries.
Authorities anticipate between 15 million and 20 million participants in Tehran alone over the next three days, a turnout that would make it the largest state funeral in Iran's history, surpassing the 1989 burial of Khamenei's predecessor, Ruhollah Khomeini.
Officials unveiled Khamenei's casket in a glass case at the Grand Mosalla, prompting waves of weeping and rhythmic chest-beating among mourners, a common practice at Shia funerals.
"Our word is one! Revenge! Revenge!" the crowd chanted, according to The Associated Press (AP).
Thousands carried red banners, a symbol associated with calls for vengeance, while billboards across the city bore Khamenei's image.
"I am here to say goodbye to my beloved leader Ali Khamenei," said Hananeh Mousavi, 27, who attended alongside her mother, adding, "I never expected to see such a day. I wish I had died before this tragedy."
Ali Kazemi, who traveled 530 kilometers (329.33 miles) from Tabriz, said: "We attended the funeral to show that we are all committed to defend our country and religion."
With temperatures expected to exceed 35 degrees Celsius (95 degrees Fahrenheit), organizers stationed water tankers to spray mist on the crowds and offered cold drinks to attendees.
Schools, mosques and sports halls were prepared to house mourners, while hotels offered 50% discounts and bus and rail networks were redirected to serve the main events.
Among the Iranian officials filing past the coffin to weep and pray was Ahmad Vahidi, head of the Islamic Revolutionary Guard Corps (IRGC), making his first public appearance since his appointment following Khamenei's death.
Vahidi had not been seen in public for fear of assassination, according to Reuters.
Parliament Speaker and lead U.S. negotiator Mohammad Bagher Ghalibaf was visibly tearful, Reuters reported. Ghalibaf had urged Iranians to turn out in force, saying "the nation's call for vengeance must ring in the ears of the whole world."
Army Chief Amir Hatami vowed that Israel and the United States "will pay for the blood of the martyred leader and all the nation's martyrs," according to Agence France-Presse (AFP).
International guests included Pakistani Prime Minister Shehbaz Sharif, whose country has mediated between Iran and the United States; former Russian President Dmitry Medvedev, attending on behalf of President Vladimir Putin; Chinese National People's Congress deputy head He Wei; and Iraqi President Nizar Amedi.
Families of Hezbollah leader Hassan Nasrallah and senior commander Imad Mughniyeh attended, as did representatives of Hamas and the Taliban government in Afghanistan, according to Reuters.
Iran warned the United States and Israel against any attacks during the funeral period.
Khamenei's coffin will lie in state until Monday, when a procession will pass through Tehran.
The remains will move to the clerical center of Qom on Tuesday, then to the Iraqi shrine cities of Najaf and Karbala on Wednesday. Burial is scheduled for Thursday at the Imam Ali Reza Shrine in Mashhad, Khamenei's home city in northeastern Iran.
Also on display in coffins next to Khamenei's were his daughter, son-in-law, and infant granddaughter, as well as the wife of his son and successor, Mojtaba Khamenei, all killed in the same strikes.
The coming days will be closely watched for any appearance by Mojtaba Khamenei, who was named supreme leader a week after his father's killing but has communicated only through written statements.
He is reported to have been wounded in the same strike, though the extent of his injuries was never made clear.
Khamenei, 86, was killed on Feb. 28, the first day of the U.S.-Israeli war with Iran, at his compound in central Tehran. His six-week funeral delay was caused by the risks of holding a large public event during active fighting.
The ceremonies were rescheduled following last month's interim truce between Iran and the United States.