As a circulating medium, money has drawn the attention of political organizations looking for a vehicle to spread propaganda. In times of war and social turmoil paper money is particularly susceptible to becoming a medium for bearing revolutionary messages.
In 1967, the Chinese Communist Party instigated riots against the Hong Kong government and put to use the circulating money of Hong Kong to propagate messages discrediting the government. The communists were
exploiting a touchy economic situation associated with the devaluation of the pound sterling and subsequent devaluation of the Hong Kong dollar. Hong Kong was a colony of the British government at the time.
The Hong Kong and Shanghai Banking Corporation issued notes in Hong Kong, and the communists took in
$10 and $100 notes and overprinted messages calculated to inflame the populace against the government. The top left corner of the overprinted $10 notes bore the famous figure of John Bull with outstretched hands and a gaping mouth. Behind his head in Chinese characters was the message, “He is so greedy that he swallows money.” At the bottom of the overprinted $10 notes were two Chinese characters meaning “Devaluation.” On the reverse side of the $10 banknotes the communists overprinted a text heavily sprinkled
with words such as “imperialism,” “banditry,” and “fascism,” and describing the British exploitation of Hong
Kong that led to the devaluation of the Hong Kong dollar.
The communists overprinted the $100 notes with a caricature of a pirate with a sack of protruding $100 notes thrown over his back. Printed on the sack were the words “Open Banditry.” In the center of the bill the communists overprinted the message, “Worth only 94.30 dollars after devaluation.” On the reverse side
the communists overprinted a text ending with the rallying cry, “fellow brothers: in order to survive we must unite together and fight to the end against the British in Hong Kong.”
During the Vietnam War, peace protesters in the United States drew peace symbols and slogans on dollar bills. At the height of the peace protests the Federal Reserve Banks withdrew the bills bearing antiwar messages. During World War II, the British authorities overprinted German military notes with propaganda messages derogatory of Adolf Hitler.
Metallic coinage may have begun as a means of advertising seaports, and the use of propaganda money demonstrates that money is a vehicle for communication. Propaganda money defaces a symbol of government—usually images hallowed by time that are typically placed on paper money—and at the same time propagates a message that discredits the government. 
See also: Siege Money
Beresiner, Yasha. 1977. Paper Money.