For the next fifteen years, from 982 to 997, High King Máel Sechnaill repeatedly led armies into Leinster and Munster, while Brian, like his father and brother before him, led his naval forces of around three hundred ships up the Shannon to attack Connacht and Meath on either side of the river. He suffered quite a few reverses in this struggle, but appears to have learned from his setbacks. He developed a military strategy that would serve him well throughout his career: the coordinated use of forces on both land and water, including on rivers and along Ireland's coast. Brian's naval forces of around three hundred ships, which included contingents supplied by the Hiberno-Norse cities that he brought under his control (particularly Waterford), provided both indirect and direct support for his forces on land. Indirect support involved a fleet making a diversionary attack on an enemy in a location far away from where Brian planned to strike with his army. Direct support involved naval forces acting as one arm in a strategic pincer, the army forming the other arm.