The revolutionary war was highly inflationary as the “continental” became nearly worthless. Confederate currency became worthless during the civil war. WWII was highly inflationary. Vietnam war was also highly inflationary.
Money is a piece of paper that entitles the bearer to some piece of the economy. During war, the non military economy shrinks. So unless you want to buy a tank or a fighter jet, there is more money around and less to buy.
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?