Marine M114 155mm howitzer of III Amphibious Corps fires in support of Tenth Army advance. On May 9, 1945, US Army Lieutenant General Simon Bolivar Buckner, Jr. ordered a coordinated Tenth Army attack for May 11. The plan of attack called for Tenth Army to renew the assault on the Shuri defenses with its two corps abreast, III Amphibious Corps on the right, XXIV Corps on the left. The initial scheme of maneuver was an envelopment of Shuri by the Marine divisions on the west and the Army divisions on the east, while a strong holding attack was maintained in the center The Tenth Army staff believed that the Japanese positions were weaker on the right and that the fresh Marine divisions had a chance for a quick break-through on that flank. Moreover, the terrain was more favorable along the western coast. The wide flanking maneuver around Shuri that later developed was not projected in the original plans. General Buckner explained on May 10 that there would be nothing spectacular. He added: "It will be a continuation of the type of attack we have been employing to date. Where we cannot take strong points we will pinch them off and leave them for the reserves to reduce. We have ample firepower and we also have enough fresh troops so that we can always have one division resting." The initial order for the attack provided for a 30-minute general preparation by the artillery just before the ground attack. This provision was revoked two days later in favor of pinpointing of targets. The new order stated that "the maximum practicable number of known enemy guns and strong points will be destroyed or neutralized" prior to the infantry assault. The attack launched on schedule, although coordinated initially along the entire front, soon broke down into a series of intense battles for particular landmarks. For ten days of continuous fighting, from Sugar Loaf on the west coast to Conical Hill on the east, the Japanese, except for local and relatively minor retreats, held tenaciously to their long-prepared positions. Finally, on May 21, after some of the fiercest action of the battle of Okinawa, the American forces were to seize the eastern slope of Conical Hill, close to the east coast, and thereby to make an opening in the enemy lines which permitted an attempt at envelopment.