As the war continued, the Union blockade proved critical in restricting goods from entering and leaving the Confederacy. Southerners faced increasing shortages of supplies, including paper and envelopes. Writers began to use whatever was handy as letter writing paper and envelopes. These items are known by philatelists as "adversity covers."
Letters and envelopes were fashioned from the backs of ledger sheets, printed circulars, blank pages in books, maps and even wallpaper. Some writers re-used envelopes by turning them inside out. Any blank or partially blank piece of paper could be pressed into service as an envelope.