J. Lawton Collins used the term in the title of his book, War in peacetime: the history and lessons of Korea (1969). Andre Beaufre focused on the term in his books, Introduction to Strategy (New York: Praeger, 1965 [Introduction la stratgie, Paris, 1963]); and Deterrence and Strategy (London: Faber, 1965 [Dissuasion et stratgie Paris, Armand Colin, 1964]).

Beaufre's history of its practical usage found that, prior to WWI, a clear line was drawn between "Peace" (the European "normal" between the Napoleanic Wars and WWI) and "War". Those situations were governed by distinct and separate rules in law, strategy, policy and politics. In law, the dichotomy was evidenced by L.F.L. Oppenheim's magisterial 2-volume treatise (1905 1st edition), International Law: A Treatise. Vol I: Peace; and International Law: A Treatise. Vol II: War and Neutrality. Both online at www.archive.org

The changes caused by WWI-WWII (followed by the Cold War) put finis to the clear distinction between "Peace" and "War". Thus, in Beaufre's terms, lawyers, strategists, policy-makers and politicians had to learn to play one piece in two different keys at the same time:

The game of strategy can, like music, be played in two keys. The major key is direct strategy, in which force is the essential factor. The minor key is indirect strategy, in which force recedes into the background and its place is taken by psychology and planning.
Thus, we have been introduced to such concepts as the "Three Block War".

That being said, there has been a reluctance to abandon the clear dichotomy between "Peace" and "War"; and the concept of "War in Peacetime" has been found unacceptable by many. That is not a right or left thing; it is not a military or civilian thing; but, it is shaped by many factors in each of us.

Yesterday's NYT Editorial illustrated to me the anti-"War in Peacetime" viewpoint - as also did some of President Obama's remarks - The End of the Perpetual War (by THE EDITORIAL BOARD; Published: May 23, 2013):

President Obama’s speech on Thursday was the most important statement on counterterrorism policy since the 2001 attacks, a momentous turning point in post-9/11 America. For the first time, a president stated clearly and unequivocally that the state of perpetual warfare that began nearly 12 years ago is unsustainable for a democracy and must come to an end in the not-too-distant future.

“Our systematic effort to dismantle terrorist organizations must continue,” Mr. Obama said in the speech at the National Defense University. “But this war, like all wars, must end. That’s what history advises. It’s what our democracy demands.”

As frustratingly late as it was — much of what Mr. Obama said should have been said years ago — there is no underestimating the importance of that statement. Mr. Obama and his predecessor, President George W. Bush, used the state of war that began with the authorization to invade Afghanistan and go after Al Qaeda and others who planned the Sept. 11 attacks to justify extraordinary acts like indefinite detention without charges and the targeted killing of terrorist suspects.

While there are some, particularly the more hawkish Congressional Republicans, who say this war should essentially last forever, Mr. Obama told the world that the United States must return to a state in which counterterrorism is handled, as it always was before 2001, primarily by law enforcement and the intelligence agencies. That shift is essential to preserving the democratic system and rule of law for which the United States is fighting, and for repairing its badly damaged global image.

Mr. Obama said the Authorization for Use of Military Force, which was passed after Sept. 11, 2001, must be replaced to avoid keeping “America on a perpetual wartime footing.” He added: “Unless we discipline our thinking and our actions, we may be drawn into more wars we don’t need to fight, or continue to grant presidents unbound powers more suited for traditional armed conflicts between nation states.”

He did not say what should replace that law, but he vowed: “I will not sign laws designed to expand this mandate further.” ...
My reaction to this verbiage is that it evinces both naivety and arrogance. Naivity because the other side also has a vote in whether a "war in peacetime" shall end. Arrogance (perhaps, hubris is a better word) because it is simply another way of declaring Pax Americana - which goes hand in hand with Bellum Americana - both spell "global hegemony".

While I appreciate the desire to go back to a simpler, more clearly-defined time, I do not believe that is possible.

Regards

Mike