I was in DC in 1963 (?) staying in quarters at Ft Meyer when the Cuban Crisis started. I watched these guys change from very good "parade square soldiers" to very good "combat soldiers" in about 2 hours. Gone was all the parade uniforms and accoutrement's to be replaced with fighting stuff.
I had only been away from the infantry for three or four years and was quite impressed with the way everything changed with probably one phone call. We were working with the US Army Band, and even they were put on standby, not as combat troop, but as sentries and such, around Washington.
All the best Drummy