In The Confederate Note Case, 19 Wall. 548, 555-557 (1874), in which it was held that parol evidence was admissible to prove that the word "dollars" in a contract made during the civil war meant, in fact, Confederate notes, the court said: "The treasury notes of the Confederate government were issued early in the war, and, though never made a legal tender, they soon, to a large extent, took the place of coin in the insurgent States. Within a short period they became the principal currency in which business in its multiplied forms was there transacted. The simplest purchase of food in the market, as well as the largest dealings of merchants, were generally made in this currency. Contracts thus made, not designed to aid the insurrectionary government, could not, therefore, without manifest injustice to the parties, be treated as invalid between them. Hence, in Thorington v. Smith this court enforced a contract payable in these notes, treating them as a currency imposed upon the community by a government of irresistible force. As said in a later case, referring to this decision, `It would have been a cruel and oppressive judgment, if all the transactions of the many millions of people composing the inhabitants of the insurrectionary States, for the several years of the war, had been held tainted with illegality because of the use of this forced currency, when those transactions were not made with reference to the insurrectionary government' Hanauer v. Woodruff, 15 Wall. 448." Again: "When the war closed, these notes, of course, became at once valueless and ceased to be current, but contracts made upon their purchasable quality, and in which they were designated as dollars, existed in great numbers. It was at once evident that great injustice would in many cases be done to parties if the terms used were interpreted only by reference to the coinage of the United States or their legal tender notes, instead of the standard adopted by the parties. The legal standard and the conventional standard differed, and justice to the parties could only be done by allowing evidence of the sense in which they used the terms, and enforcing the contracts thus interpreted."