Macbeth ruled Scotland for 17 years, the first 10 of which were peaceful. However, the final 7 years were marked by paranoia as Duncan's sons had grown up and were plotting to invade Scotland and overthrow Macbeth. While Shakespeare portrays Duncan as an old man killed in his sleep by Macbeth, historical accounts say Duncan was only 36 and killed in battle after many considered him an incompetent ruler facing rebellions. Lady Macbeth had a blood feud with Duncan's family dating back to her grandfather's death in battle against Duncan's grandfather.