commander-in-chief 
noun (plural commanders-in-chief)
1An officer in charge of all of the armed forces of a country, or a major subdivision of them.The wartime direction of all troops and forces involved in an operation was a centralized one, with commanders-in-chief and their staff in charge of command and control during military operations....
- There are paintings and photographs of generals, lieutenants, sergeants, privates, secretaries and commanders-in-chief.
- The commander-in-chief, Field Marshal Sir Douglas Haig, was Scots, but could only offer to out-produce and out-slaughter the Central Powers.
1.1A politician or head of state in supreme command of a country’s armed forces.Well, they're certainly concerned, but I think we give the president, our leader, our commander-in-chief, the benefit of the doubt....
- It is far more familiar, unfortunately, to consider a president as a commander-in-chief of a nation's armed forces.
- And of course, the president's their commander-in-chief all the more so.