|Predecessor||Alton Celtigar (Hand of the King)|
|Successor||Alyn Stokeworth (Hand of the King)|
|Died||In 34 AC|
After Aegon heard of an attack on Tall Trees Town in the Summer Isles, Ser Osmund and Grand Maester Gawen were charged with the overseeing and raising of walls around King's Landing. Work on the walls commenced in 20 AC and continued until 26 AC. In 29 AC and again 30 AC, Ser Osmund and Lord Aethan Velaryon, lord admiral and master of ships, led campaigns in the Stepstones to root out the Lysene pirate king Sargoso Saan. They were accompanied by the young Prince Maegor Targaryen.