In August 2004 , at the height of the second uprising that year that Mr. Sadr led against American forces , he flew back to Iraq from a hospital bed in London and within a matter of hours forged an agreement that won Mr. Sadr 's agreement to withdraw his fighters from Najaf 's Golden Mosque in return for American agreement not to storm the shrine and to allow Mr. Sadr to slip out of the city unharmed .