Major conflict began on 5 August, when the Mahdi Army (MA) attacked an Iraqi Police Station at 1 am. Their first attack was repelled but the MA regrouped and attacked again at 3 am. Soon after, a quick reaction force (QRF) from the MEU (B 1/4) was dispatched at the request of the governor of An Najaf. Around 11 am the QRF came under heavy machine gun and mortar fire from the Mahdi Army within the Wadi-us-Salaam, the largest cemetery in the Muslim world approximately 7 miles squared. The cemetery has been layered over the centuries resulting in large underground tombs, tunnels and surface monuments, many reaching two stories tall. The Soldiers of 1/5 Cav fought across this inhospitable terrain and under it in some of the first tunnel fighting seen since Vietnam.