Well, this is awkward. One of the many beliefs shared by the majority of festival goers was a dislike for the US military. Like many in society at the time, they believed that the Vietnam War had been going on for far too long, they weren't winning it, and it was time for peace. They also didn't believe in the cause and took issues with soldiers who went to fight for it.
That attitude came back and bit them a little when food, water and medical care ran out, and there was only one organization capable of airlifting the essential supplies in. Yes, you guessed it, the army stepped in and delivered not only the supplies, but many of the festival's performers. Trying to ward off the possibility of festival goers attacking the military aircraft, an announcer took the microphone on the main stage and shouted 'They are with us, man, they are not against us' in order to encourage safe passage.