From Academic Kids
While well-known Commanders-in-Chief often have been senior generals, many countries have the rule that the Head of State is Commander-in-Chief in times of peace. Historically, the term "commander-in-chief" was first used by Charles I of England in 1639. Colonial governors in the future United States used the title.
During times of war, national governments often establish regionally-based Commanders in Chief to deal with a particular theater of war. Though subsidiary to the national Commander in Chief, such local-level Commanders in Chief usually have full decision-making authority in order to improve efficiency during war.
Democratic monarchies, Commonwealth
In democratic monarchies, the King or Queen is the symbolic Commander-in-Chief, though the active authority is exercised by the Prime Minister and the subordinate defense ministers. In a few Commonwealth Realms, Commander-in-Chief is the Governor-General (though they will usually perform this role in the Queen's name), while in colonies the Commander-in-Chief is the leader of the colonial power. In France, the President of the Republic has a title of Chef des Armées ("Commander of the Armies"), which is a legacy of the monarchy.
Before 1948 the Commander-in-Chief in India reported to the civilian Governor-General of India since independence the duties of the two posts were merged into a single office, the President of India, who in turn reports to the government of the Republic of India. This model has been emulated by most other Commonwealth republics.
In France, the President of the Republic holds the title of "Chef des Armées" ("Chief of the Armies"). He is the supreme authority for military affairs, and is the only competent authority for the use of nuclear power.
Since the reign of Louis XIV France has been strongly centralized. After crushing local nobles engaged in warlordism, the Kings of France retained all authority ("Droit Divin", "divine authority") with the help of able yet discreet Prime ministers (Mazarin, Richelieu).
The 1789 Revolution transferred the supreme authority to the King (in the context of the short-lived constitutional Monarchy), then to the multi-member Comité de Salut Public during the Convention, and later to the Directoire, before being regained in the hands of Napoleon Bonaparte alone.
The Restauration restored authority of the King, in an absolute, then constitutional way before being overthrown by the Second Empire. The following Third Republic was a parliamentary system, where the military authority was held by the President of the Council (Prime Minister).
During World War II, Marechal Pétain usurped power and held the supreme authority. The following and short-lived Fourth Republic was a parliamentary system, which was replaced by the Fifth Republic, a semi-presidential system.
In a time of declared war or national emergency, the Federal Council appoints a General (in normal conditions, Swiss general officers hold the title of "colonel"). The General acts as the highest military authority, but is subordinate to the Federal Council, which holds the supreme authority.
Four Swiss generals were appointed in its history, General Henri Dufour during the Swiss Civil War, General Hans Herzog during the Franco-Prussian_War, General Ulrich Wille during the First World War, and General Henri Guisan during the Second World War ("la Mob", "the Mobilisation"). Although Switzerland remained neutral during the latter three conflicts, the threat of having its territory used as a battlefield by the much bigger war parties of Germany and France required mobilization of the army.
In normal times, military units can be dispatched for peace-keeping or disaster response by the Federal Council.
The Constitution of the United States gives the title to the President of the United States, who "shall be Commander-in-Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States" (See the 1941 Declarations of War (http://www.yale.edu/lawweb/avalon/wwii/dec/decmenu.htm) against Japan and Germany for how this call is made).
In the United States, the Goldwater-Nichols Defense Reorganization act of 1986 added a new level of CINC. Under Goldwater-Nichols regional CINCs were created to bring a local supreme commander to a conflict. The most well known of which is CINC CENTCOM, who was Norman Schwarzkopf during Operation Desert Storm.
Commander-in-Chief reserved for the President
On October 24, 2002, the U.S. Secretary of Defense announced that the title of Commander-in-Chief would be reserved for the President, and that armed forces CINCs would shorten their title to "commander." They are typically referred to as combatant commanders, heading what are now know as combatant commands. The title has taken on prominent importance in the political debate in the United States in the context of the "War against Terrorism"  (http://www.washingtonpost.com/wp-dyn/articles/A16750-2004Sep12.html).
Since the September 11, 2001 attacks on the World Trade Center and the declaration of the War on Terror, American media has increasingly referred to the President as the "Commander-in-Chief", even in civil affairs. In the discourses of opponents, this is often done when discussing the restriction of civil rights, such as with the Patriot Act, suggesting a comparison between the President and the military leaders of dictatorial countries; but ambiguous statements are also regularly featured in statements of personalities favorable to the Bush administration, in such a way as to suggest a Commander in Chief of the USA themselves:
- "A political candidate who jumps to conclusions without knowing the facts is not a person you want as your commander in chief when it comes to your security." (Good illustration, since the "Commander in Chief" part of the presidential charge always comes to security, this somehow implies that the "commander in chief" has taken over other parts of the presidency -- Bush campaign line, cited by John F. Kerry  (http://www.cnn.com/2004/ALLPOLITICS/10/28/election.main/index.html))
- "No one should dare to even think about being the Commander in Chief of this country if he doesn't believe with all his heart that our soldiers are liberators abroad and defenders of freedom at home." ?Zell Miller, see 2004 Republican National Convention
Canada's Commander-in-Chief Situation is slightly complex. The British North America Act of 1867 states: "The Command-in-Chief of the Land and Naval Militia, and of all Naval and Military Forces, of and in Canada, is hereby declared to continue to be vested in the Queen."
In 1947 King George VI transferred the title of Commander-in-Chief to the Governor General of Canada in order for Canada to have a resident C-in-C and to reinforces Canada's independence from the military of Britain. However, the King did not transfer his role, but rather transferred its duties to the Governor General.
It is therefore safe to say, that the Sovereign of Canada, presently Elizabeth II, is C-in-C, but allows the Governor General to perform that role.