The fact he is calling for this really says a lot about how over-extended our military is right now.
"One of the first steps we can take together is to add to the ranks of our military - so that the American Armed Forces are ready for all the challenges ahead. Tonight I ask the Congress to authorize an increase in the size of our active Army and Marine Corps by 92,000 in the next 5 years. A second task we can take on together is to design and establish a volunteer Civilian Reserve Corps. Such a corps would function much like our military reserve. It would ease the burden on the Armed Forces by allowing us to hire civilians with critical skills to serve on missions abroad when America needs them. And it would give people across America who do not wear the uniform a chance to serve in the defining struggle of our time. "
Historically, these civilian forces have played important roles during wartime. For instance the Nazi Stormtroopers, or Sturmabteilung, also known as the SA or Brown shirts, played a key role in Hitler's rise to power since they were civilians who's primary job was busting up beer halls to silence any dissent.