[hugh3]

then I remembered that the military leadership and tactics during The Great War were pretty damn lousy (e.g. trench warfare)

What's so lousy about trench warfare? I mean, yes, it sucks, but it's a Nash equilibrium given the technology at the time (very good machine guns, lousy tanks and aircraft). If your enemy has trenches, you need trenches too. What else would you have done?

[eru]

Oh, you could have stayed in the trenches---but don't order any attacks. Just wait for your enemies to be dumb enough to attack first. Just bleed them dry with defence.

(I heard that the Belgian king was held in high esteem by the normal Belgians for not ordering those suicidal attacks.)

[werpon]

It's actually impossible to provision such a big army when essentially every adult man is in a trench.

World superpowers would have gone bankrupt had they used this tactic.

[carpo]

But then when they don't attack you have 2 armies sitting and waiting until the supplies run out (assuming the other learns you are not going to attack back). So when one realizes they will run out first, or another army is coming to cut their lines, or the city behind them is starving, or one side drops mustard gas into the other trench ... what do you do?

[eru]

If the other guys are attacking, you wait them out. Defence was cheaper than attack in those days.

IF the other guys are also defending, you can think about, maybe, peace?

[jwhite]

It wasn't a symmetric situation though. The Germans generally held better ground because they were the ones who initially made the decision to entrench after First Marne. They chose the best defensive positions they could find, and the French and British had to make do (although I guess there would have been exceptions, such as the Verdun sector). Politically, the French and British couldn't just sit there and do nothing or sue for peace because they had a vast enemy army encamped on their territory -- what terms do you think the Germans would have imposed when they were clearly at the advantage? Under these circumstances they had to launch offensives, and given that they were at war and in stalemate, this was not a mad decision although it seems like it to us a hundred years on. The real madness was in letting the war happen in the first place, and the real tragedy was the criminally slow pace at which the general staff on both sides learned the errors of their pre-war doctrines.

[carpo]

Yes, peace would be the best outcome, but there is probably some overarching reason for the war that won't be solved by two armies deciding not to fight for tactical reasons.

[eru]

The Germans could have chosen to fight in the east, where they actually won historically, and decide to sit it out in the west.

[bdunbar]

What else would you have done?

I'd do what actually happened: innovate with technology and tactics to break through the trench line.