"But Tom, how can there be a major battle for anywhere - George told us that major military activity finished more than a year ago. "

You meant to say major combat operation.
When the miltary moves around 100,000 troops in one of the longest & fastest assaults in history, they call it an operation- a major combat operation. And that major combat operation was completed about 2 years ago. One of the factors that made it a major combat operation was it included air force elements, army elements and naval elements and this is called a joint operation. The jointness quality of the operation also included other nations involved in the miltary assualt.
The navy was involved in this major combat operation mainly by each carrier having capablity of launching up to 80 combat aircraft and each also of ships of the carrier group could launch tomohawk cruise missiles [though primary role of these destroyers was to maintain defensive fence to protect the carrier from attack]. Naval carrier battle groups leave their home ports and have tours which may last around year and involve travelling around the world, these tours can include specific mission, e.g. given orders to be involved in the Desert Storm operation would been an example of a mission. Or which they near a location of natural disaster such as tsunami, they can be given the mission to get the area quickly and assist the survivors.