During the early 17th century, England's relative naval power deteriorated, In the course of the rest of the 17th century, The office of the Admiralty and Marine Affairs steered the Navy's transition from a semi-amateur Navy Royal fighting in conjunction with private vessels into a fully professional institution, a Royal Navy. Its financial provisions were gradually regularised, it came to rely on dedicated warships only, and it developed a professional officer corps with a defined career structure, superseding an earlier mix of sailors and socially prominent former soldiers.