Wasn't it's single purpose, but if you want a source that says exactly that, let me give you the first few of a search:
WASHINGTON -- The deployment of nearly 50,000 National Guard troops from 50 states as part of the Hurricane Katrina relief effort has exposed debilitating equipment shortages in a force already stretched thin by three years of deployments in Iraq and Afghanistan.
Lt. Gen. Steven Blum, head of the National Guard, said in an interview that the needs of Guard units overseas have left troops at home without modern communications and night vision equipment, as well as the vehicles necessary for Guard troops to traverse neighborhoods flooded in the wake of Katrina.
Guard units stretched thin
AP) The National Guard is stretched so thin by simultaneous assignments in Iraq and the hurricane-ravaged Gulf Coast that leaders in statehouses and Congress say it is time to reconsider how the force is used.
National Guard Stretched Thin - CBS News
Army National Guard units that'd already served the maximum time on active duty, in combat, are being told that the rules have changed, and they're again being called back for Iraq service.
It doesn't matter that those Guard units were ordered to leave virtually all of their equipment in Iraq and have had none of it replaced so that they might actually train for the eventuality that has befallen them. Nor does it matter that there may not be equipment and vehicles waiting for them in Iraq when they get there.
An Army Stretched Thin