The debts to foreigner governments were mostly paid and paid in specie, although, payments were suspended for a time and not paid in full until after the war. The bonds issued by states and the general government were sold to bondholders at large. They were mainly wealthy Americans. Much of this debt was assumed by the Federal government and the states, but to the extent that these bonds were not paid it was generally American bond holders who suffered the loss. Regular Americans suffer losses in the monetary inflation of the war financing to the extent that the government obtained goods with printed money before prices rose. So, the other beneficiaries of the war spending were those who obtained the new money early in the process. Morris made sweetheart deals, for example, with companies other than his own in war procurement spending.
It is Murray Rothbard’s thesis that the war could have been won and won more readily through guerrilla tactics instead of by a conventional army approach.