Answer:
The battle between Sir Tristram and Sir Marhaus led to the death of Sir Marhaus and even Sir Tristram was also wounded as the tip of the sword used by Sir Marhaus was poisoned.
Step-by-step explanation:
Sir Marhaus is a knight in the kingdom of Ireland under King Anguish while Tristram is a knight from Cornwall under the rule of King Mark. King Mark had stopped paying tribute to the king of Ireland and thus was the reason of the battle between the two knights. This resulted in the death of Sir Marhaus as he, being much older than the young and big Sir Tristram, wasn't a capable match for him. Even Tristram was wounded as Sir Marhaus's spear was poisoned and he had to be taken to the kingdom of Ireland if he was to be healed.