From left to right --
Fighter Aircraft Sukhoi of the Operation TRIKORA - A 50th anniversary Indonesian stamp issued on 5 October 2011. The operation TRIKORA was part of the efforts of Indonesia to regain western New Guinea from the Netherlands.
60th Anniversary of Victory in WWII - A Russian stamp issued on 5 April 2005.
The Liberty Bell - As freedom is a a theme related to war & peace, I reckon this stamp can be categorized under this theme. A USA Forever stamp issued on 7 August 2009
Enfant de paix - From a 12-set warm & vibrant Les Petit Bonheurs French stamp booklet, this is my favorite among these 4 stamps. The booklet was issued 3 years ago, 12 November 2013.
For more stamps on the theme war & peace, visit the page - See it on a postcard and other participants of the linky.