Shamefully, our own government was one of those that opposed the British use of force. But fortunately British prime minister Margaret Thatcher ignored "world opinion" and took back the Falklands.
The most catastrophic result of "peace" movements was World War II. While Hitler was arming Germany to the teeth, "peace" movements in Britain were advocating that their own country disarm "as an example to others."
British Labor Party Members of Parliament voted consistently against military spending and British college students publicly pledged never to fight for their country. If "peace" movements brought peace, there would never have been World War II.
Not only did that war lead to tens of millions of deaths, it came dangerously close to a crushing victory for the Nazis in Europe and the Japanese empire in Asia. And we now know that the United States was on Hitler's timetable after that.
For the first two years of that war, the Western democracies lost virtually every battle, all over the world, because pre-war "peace" movements had left them with inadequate military equipment and much of it obsolete. The Nazis and the Japanese knew that. That is why they launched the war.
"Peace" movements don't bring peace but war.