Cease fire that led to them splitting up
Common good means for the good of the public or the many. One example of a scenario of contributing to the common good is that a person follows the laws of the country like traffic. It is a common good because following the rules will give order thus contributes to the common good while not following the rules only served the person own's interest.
When they wrote this song they made it about the Vietnam war. They felt that rich politicians started the wars for their benefit and have all the poor people die for them.
His son was killed in a train wreck. What's worse, because his wife disagreed with his agreement to be president, she blamed him for their sons death
