The quote "I think it is peace in our time" was made by Neville Chamberlain in 1938. It was made after he had signed the Munich Agreement with Adolf Hitler, which was a contract that permitted Germany to annex parts of Czechoslovakia in exchange for a guarantee of peace. Chamberlain believed that this agreement would bring an end to the looming danger of war in Europe. Sadly, this was not the case and World War II broke out just a year later on. The quote has given that ended up being a symbol of naivety and wishful thinking, as Chamberlain's optimism was not recognized. It acts as a suggestion of the importance of being sensible and cautious when handling worldwide relations.
"When the principles that run against your deepest convictions begin to win the day, then the battle is your calling, and peace has become sin. You must at the price of dearest peace lay your convictions bare before friend and enemy with all the fire of your faith"