By the morning of 23 February, Mount Suribachi was effectively cut off above ground from the rest of the island. The Marines knew that the Japanese defenders had an extensive network of below-ground defenses, and that in spite of its isolation above ground, the volcano was still connected to Japanese defenders via the tunnel network. They expected a fierce fight for the summit. Two small patrols from two rifle companies from the 2/28 Marines were sent up the volcano to reconnoiter routes on the mountain's north face. The recon patrols made it to the summit and scrambled down again, reporting any contact to the 2/28 Marines commander, Lieutenant Colonel Chandler W. Johnson.