Ferguson. Brown II, issued in 1955, decreed that the dismantling of separate school systems for Black and white students could proceed with "all deliberate speed," a phrase that pleased neither supporters or opponents of integration.
Because it weakened the Japanese morale. The IJN would no longer be capable of operations in the Pacific Southwest because their resources were low. They were also still reeling from the losses at Midway.
The Americans secured Henderson field, a major airfield that prevented the Japanese from spreading south into Australia. The Aussies would be helpful in Operation D-Day.
US-Australian supply lines were no longer under threat. It's why the IJN tried to take the island in the first place.