User blog comment:Duchland/The Two Great Wars in one?/@comment-257949-20100729163809

If trench warfare was adopted even more liberally, as in on the eastern front too, then World War One could have been greatly extended. However, in order to maintain this then we would need to see the disappearance, or at least reduction, of two factors:


 * The Spanish Flu, which would reduce manpower and possibly give one side the incentive to go on an offensive and bring about a quicker end to the war


 * The invention of the tank, which provided a (relative) increase in mobility. Huge armoured thrusts were planned for 1919; these might have greatly hastened the collapse of one side or another. The introduction of the tank must be pushed back several years to allow the war to continue without rapid change, and subsequent defeat of one side.