Military Ranks

What is the traditional title for the highest-ranking officer in the United States Army and Marine Corps?

In ancient Rome, what was the highest military rank typically held by a general in command of a single legion?

In medieval Europe, what title was often given to a noble appointed to lead a military campaign on behalf of a king or lord?

In the Ottoman Empire, what was the highest military rank and title, often held by the commander-in-chief of the Ottoman military forces?

During the Napoleonic era, what was the highest rank in the French military, held by Napoleon Bonaparte?