This is how stupid, catastrophic wars start. Small. Tiny. Incidents. A burned flag; a minor exchange of fire on the border; a small false flag attack; a leader assassinated.
Suddenly, the emotions of millions of people come into play, and everybody demands a war against the other side.
In some societies the leaders take the people to war by manipulating them, but in other societies the opposite occurs - the people overrun their timid leaders and take matters into their own hands.