Answer:
In William Shakespeare's play "Macbeth," Macbeth killed the guards (grooms) of King Duncan and then used the excuse that he did so in a fit of rage because he believed they had killed the king. However, Macbeth's real reason for killing the guards was to cover up his own guilt and prevent them from speaking out against him. Macbeth had planned and carried out the murder of King Duncan in order to fulfill the witches' prophecy that he would become king, and he knew that the guards could potentially reveal his involvement in the crime. By killing the guards, Macbeth effectively silenced any witnesses who could have testified against him and helped to ensure his own rise to power.