This attributed to Sun Tzu and his book The Art of War. Actually James Clavell’s foreword in The Art of War http://www.scribd.com/doc/42222505/The-Art-Of-War states http://www.collegetermpapers.com/TermPapers/History_Other/Sun_Tzu_vs_The_Wisdom_of_the_Desert.shtml, “’the true object of war is peace.’” Therefore the quote is stated by James Clavell, but the true origin of Clavell's quotation is unclear. Nonetheless the essence of the quote, that a long war exhausts a state and therefore ultimately seeking peace is in the interest of the warring state, is true, as Sun Tzu in Chapter II Waging Wars says that "There is no instance of a country having benefited from prolonged warfare. It is only one who is thoroughly acquainted with the evils of war that can thoroughly understand the profitable way of carrying it on." This has been interpreted by Lionel Giles http://www.dutchjoens.info/SunTzu%20-%20Art%20of%20War.pdf as "Only one who knows the disastrous effects of a long war can realize the supreme importance of rapidity in bringing it to a close."
Dr. Hiroshi Hatanaka, President of Kobe College, Nishinomiya, Hyōgo, Japan is recorded as saying "the real objective of war is peace" in Pacific Stars and Stripes Ryukyu Edition, Tokyo, Japan (10 February 1949), Page 2, Column 2.
Misattributed
“True peace is not merely the absence of war, it is the presence of justice.”
Pt. 7
Social Insurance and Allied Services (1942)
The Things They Carried (1990), How to Tell a True War Story
Remarks of President Barack Obama To the People of Israel at Jerusalem International Convention Center in Jerusalem, Israel (21 March 2013) http://www.whitehouse.gov/the-press-office/2013/03/21/remarks-president-barack-obama-people-israel
2013
“In peace, prepare for war. In war, prepare for peace.”
Sometimes erroneously prepended to the opening line "The art of war is of vital importance to the State", but appears to be a variation of the Roman motto "Si vis pacem, para bellum". It's not clear who first misattributed this phrase to Sun Tzu. The earliest appearance of the phrase in Google Books is 1920, when it appeared in a pharmaceutical journal, but no attribution was given then.
Misattributed
Source: Songs of the Soul (1971)
Context: War forgets peace. Peace forgives war. War is the death of the life human. Peace is the birth of the Life Divine. Our vital passions want war. Our psychic emotions desire peace.
"Ceremony of the Innocent: A novel", first edition Doubleday, 1976, p. 218
1970s-
