On August 19th, after days of US bombings and hundreds of deaths, Al-Sadr ordered his fighters to hand over keys to the Shrine of Ali to Iraq's top religious authorities. Unfortunately, Grand Ayatollah Ali al-Sistani was in the UK at the time receiving medical treatment for a bad heart, so fighting continued for another week until he finally returned on August 25th.
On Friday August 27th, the standoff in Najaf ended as thousands of Sistani's supporters flooded the mosque mixing with Sadr's supporters and giving them an opportunity to leave the Shrine without fear of attack from US forces.
so... after 569 Iraqis were killed and 785 injured, after attacking the most sacred Shia shrine, and after destroying parts of the biggest and most sacred Shia cemetery in the world... [in] comes the "Grand" Sistani and solves the crisis in 10 minutes. - Read in the Middle
While the Shiite leadership in Iraq claims to oppose the US occupation, Sistani has been largely silent about US actions and has focused more of his energy on the Shiite power struggle than on the occupation or Iraq's many other problems. The main result of the siege on Najaf was a brief increase in Sistani's popularity and a change in venue for the conflict between Shiite radicals and US forces. Within weeks of what was touted as a peace agreement, fighting was on the increase in Sadr City as well as in Basra.