Clarification: I am a moderate pacifist.
A moderate pacifist recognises war as wasteful and something to avoid, but does not reject the concept of self-defence outright. Wars of choice are evil, but wars of necessity are often the lesser evil compared to surrendering to demands.
I served in the German military with good conscience because back then it was not usable for a war of aggression (yet). My moderate pacifism was fully developed only once I learned (in 2001) about the propaganda lies that were used by warmongers to enable the Kosovo Air War against Yugoslavia. I felt silly for falling for these lies despite my then already extensive knowledge of history and military history. My patience with the pro-war side was exhausted completely.
My stance is thus to keep a calm head, think rational, keep the proportions in mind (errorists are a mere nuisance compared to the real public health hazards, and the so-called "counter-terrorism" efforts are inefficient compared to many not yet enacted life-saving policies if not even exacerbating the problem). Wars of choice are a no-go, save for a tiny exception; intervention against genocide that's been proved to happen beyond reasonable doubt.
Wars of necessity on the other hand - others attacking us (for real, not puny errorists) or collective self-defence - should provoke an altogether opposite approach:
Total war from the start, tit-for-tat regarding nuclear warhead employment, and a campaign that leads to end the war as soon as possible. The only demand should be status quo ante. Any more ambitious demands would only prolong the war.
In short, I am convinced we should abstain from warfare unless it's forced on us, and then we should do nothing less than unleash the beasts of war.
Frankly, despite all the wet paper bag talk, I suppose we all know mankind doesn't want my country to unleash the beasts of war ever again. Thus simply don't attack us or our allies unless they attacked you first.