These are certainly not the most recent examples available, as regarding what happens when America goes to war.
In any case, whereas Confederate currency became "worthless," indeed--what else might be expected, considering the outcome of the Civil War?--US currency certainly recovered.
So the question remains: If WWI and WWII did not "destroy [the] western monetary system" and/or destroy "capitalism in general," why should one suppose that some future war would do so?
The western monetary system during ww1 and ww2 was based on gold and the USA had the most and also produced the most.
Not true now.
Plus, in ww1 and ww2, the usa suffered very little damage on their home turf.
that won’t be the case in ww3.