The correct answer to this open question is the following.
The event surrounding Shays's Rebellion that occurred first was "Massachusetts taxed land to pay the Revolutionary war debts."
In 1786, Daniel Shay led a group of former soldiers to attack several public properties such as courthouses. After the end of the Revolutionary war, those people became farmers and opposed to heavy taxation to pay for the war debt. The government's economic measures had causes poverty and many people lost their homes. That is why they rebelled, attacked the property of the government and those incidents became a total military conflict in 1787.