Iraqi forces in the old town of Umm Qasr put up unexpectedly strong resistance, requiring several days' fighting before the area was cleared of defenders.The U.S. Marines withdrew from the area as they were too close to the target and, after 3 or 4 hours, the 15th MEU, reinforced by two Abrams tanks continued their advance to Umm Qasr.Intense machine-gun and RPG fire directed at the US Marines prevented them moving forward to identify their targets, so they called in air support.The Navy Seals and SWCC would later hand over the remaining Iraqi prisoners to British Royal Marines at Umm Qasr for detention.[11] Brigadier Dutton knew the 15th MEU needed more time but they were scheduled to join up with the I Marine Expeditionary Force within the next 2 days, so he decided to relieve the unit and that 42 Commando could take over.As the waters came under the protection of the coalition forces, SBT 20 detachments served a crucial role in securing oil delivery stations along the gulf throughout the myriad of mine fields.