Answer
At the Battle of Tewkesbury in 1471, Margaret of Anjou's son, Edward of Westminster, was killed. This decisive battle marked the end of the Lancastrian challenge to the Yorkist dynasty during the Wars of the Roses. Edward, the only son of King Henry VI and Margaret, was just 17 years old at the time of his death, leaving Margaret a grieving mother and effectively ending the Lancastrian line of succession.