why were Magua so angry with the british ? whywas it important to comfront Col. monro face to face ? What did Magua do ?

They don't say exactly when, but Magua's village was attacked by the British and Colonel Munro was the commanding officer of the army that attacked them. In the fight, Maguas children were killed and Magua was taken captive as a slave. When Magua became blood brother to the Mohawks and was released from captivity, he learned that his wife married another man because she thought Magua had been killed. If was important for Magua to take Colonel Munros life himself and wipe out his seed (kill his children) because Munro killed his children. Although we can tell in Munro's face that he had no idea who Magua was or what he had done to Magua. This we can assume it had been years since it all happened. What did Magua do? He cut out Colonel Munro's heart during the Massacre of the evacuees from Fort William Henry.