The island is dominated by Mount Suribachi, a dormant volcanic cone at the southern tip of the island. Tactically, the top of Suribachi was one of the most important locations on the island. From that vantage point, the Japanese defenders were able to spot artillery accurately onto the Americans—particularly the landing beaches. The Japanese fought most of the battle from underground bunkers and pillboxes. It was common for Marines to disable a pillbox using grenades or flamethrowers, only to come under renewed fire from it a few minutes later, after replacement Japanese infantry arrived into the pillbox through a tunnel. The American effort concentrated on isolating and capturing Suribachi first, a goal that was achieved on February 23, four days after the battle began. Despite capturing Suribachi, the battle continued to rage for many days, and the island would not be declared "secure" until 31 days later, on March 26.