 Complete the following phrase:  Many Regiments and Brigades serving in the XXII Corps were only temporarily assigned to it. Some mainly served during times when they were reconstituting due to battle casualties, while others were trained in the vicinity of Washington before going into the field. Yet others were heavy artillery regiments assigned to the fortifications surrounding the capital. Many units, including heavy artillery regiments, left when more soldiers were needed during Grants Overland Campaign and continued through the 