"Oishi and the others had no choice, but revenge." I strongly believe this, because their master Lord Asano was executed for the death of Kira, but Kira did not die. They lost a great master because of such a miserable man. The people of Ako had to leave their native land and most of their possessions had to be left behind. Oishi and his men remained patient and tried to stay calm. They decided to wait until word came about the petition that Oishi wrote, but their was never any word. The men of Ako were made of fools. They lost hope, but gained fire power. They wanted revenge on that horrid man Kira, who was the cause of such atrocities. Oishi agreed to this and they were going to take revenge on Kira and show him what it felt like when Lord Asano was executed. One must take vengeance on another human being, when they have done everything they possibly can, to handle matters in a different way.
A man and his men must indefinitely protect the honor of their deceased master and his land. It just wasn't right Kira being alive and Lord Asano being dead, Lord Asano's wife being separated from her daughter, and the confiscation of Lord Asano's property. "Oishi and his men had no choice, but to take revenge." The men of Ako had enough, they were going to defend their master's honor and put his spirit to rest.