Since prehistoric times, warring rulers have recognised the importance of weakening the morale of opponents. Often the battle for hearts and minds is as pivotal to victory as any physical fighting. As technology has developed, so has the range and capability of psychological warfare tactics. This article will examine one aspect of psychological warfare; airborne propaganda. Airborne propaganda takes many forms, including: the aerial distribution of printed material; balloon drops; and disruptive sonic soundwaves blasted from 30-foot speakers. Airborne propaganda has been used, with great impact, to threaten destruction, prompt surrender, offer rewards, counter disinformation, and provide humanitarian assistance.
The Franco-Prussian War of 1870 saw the first documented use of manned balloons as carriers of mail, as well as propaganda leaflets. As Prussian forces surrounded the city of Paris, telephone lines were cut, and messengers captured. Innovative Parisians used balloons to maintain contact with the outside world, with over 60 balloons released. One such balloon, deployed from the city, was tasked with dropping government proclamations over Prussian troops that stated the following (in German):
Paris defies the enemy. The whole of France rallies. Death to the invaders. Foolish people, shall we always throttle one another for the pleasure and proudness of Kings? Glory and conquest are crimes; defeat brings hate and desire for vengeance. Only one war is just and holy; that of independence.
This act was revolutionary, and provoked real European interest in military air forces, over the next two decades French, British, German, Italian, American, and Russian balloon forces were established. Over 150 years later, airborne leaflets still have their role to play in psychological warfare.
The Neptune, the first balloon used to carry mail during the Siege of Paris, 23 September 1870.
First World War
The First World War, 1914-1918, is often agreed to be the start of modern psychological warfare. An array of social, political, commercial and technological factors produced a wide range of media through which propaganda could be disseminated. Furthermore, the development of military technology enabled critical changes in the use of aviation in warfare. Aerial leaflet drops may have begun tentatively, but they developed into a substantial weapon of psychological warfare. 1912 brought the formation of the Royal Flying Corps, the air arm of the British Army, and a pre-runner to the Royal Air Force (RAF). During the First World War aeroplanes went from largely being used for surveillance, to taking an active role in disseminating propaganda, reconnaissance, and active combat. These developments culminated in large scale aerial leaflet drops being utilised by all sides.
The British Royal Flying Corps dropped leaflets over German trenches and territory in an attempt to induce German troops to surrender. These propaganda leaflets included reports of the humane conditions in the British prisoners of war camps, surrender notices, and anti-Kaiser material. Paul von Hindenburg, German general and statesman who led the Imperial German Army during this war, testified to the successful distribution of British leaflets.
Our soldiers have delivered to the authorities the following number of hostile handbills: in May 34,000; in June 120,000; in July 300,000.
Severe penalties were handed out for the offence of not handing in enemy propaganda. Hindenburg himself attested to their effectiveness, admitting that ‘many thousands consumed their poison’. The success of this propaganda campaign led to orders that German troops should attempt to shoot down leaflet dropping pilots. Flights proved increasingly dangerous, the German government threatened to kill any pilots captured with enemy propaganda leaflets. To combat this the British began to look for a safer and cheaper form of aircraft. Their solution was the use of unmanned balloons, technology had developed since the manned balloon drops of the 1871 Franco-Prussian War, to allow for free-floating balloons. By March 1918 the balloon operation was active, and by the Armistice of November 11th, over 35,000 balloons had been launched, with more than 20 million leaflets dropped.
Preparation for a balloon launch with attached propaganda material.
Propaganda was not just used to evoke despair and encourage surrender in the First World War. Occasionally aircraft were a welcome sight. From 1915 to 1918 the Allied forces used aircraft and balloons to drop propaganda over occupied France, Belgium and Italy. This propaganda focused on combatting German psychological warfare, as well as disseminating news of the progress of the war. Le Courrier de l'Air was a newspaper printed in London and airdropped over occupied France and Belgium by way of unmanned paper balloons. The perceived success of Le Courrier de l'Air led to these tactics being resurrected during the Second World War.
Header of Le Courrier de l’Air.
Second World War
The Second World War was a total war. With so much at stake the UK government created the Central Office of Information to act as the country’s marketing and communications agency. This agency not only produced propaganda to steady the morale of the British people, it also created propaganda targeted at enemy nations for dissemination more widely, which aimed to weaken morale. The distribution of propaganda leaflets remained a key tactic during the Second World War, throughout the war the Allied powers dropped an estimated 6 billion leaflets on Western Europe alone. During the very first days of the war in September 1939 leaflets were dropped by the German military in the attack on Warsaw, so began an unprecedented airborne propaganda campaign on all fronts.
The 1940s brought new technological developments which aimed to increase the amount of leaflets that could be safely dropped by pilots. One of these innovations was suggested by British Air Officers; a proposal to construct a special bomb to disperse leaflets over enemy territory. The most successful of these bombs was the ‘Monroe bomb’, invented in 1943 by United States Army Air Forces Captain James Monroe. The Monroe bomb is said to have dropped over 500 million leaflets in Europe during the Second World War.
Royal Artillery gunners fill 25-pounder shells with leaflets. Roermond, The Netherlands, January 1945.
To measure the effectiveness of the vast leaflet campaigns in Europe, historians can look at whether actions urged in particular areas were acted upon. For example, there was a widespread propaganda campaign calling for the sabotage of enemy fuel transports, one report attests to the effectiveness of this campaign, stating that ‘only the region of Upper Silesia has, so far, escaped these attacks…By the end of June, there had been destroyed more than 70% of monthly production of high-octane gasoline’. Evidently, the propaganda campaigns were having an impact on actions on the ground.
At the end of the war President Eisenhower paid tribute to his ‘Skyewarriors', stating that 'the exact contribution of psychological warfare toward the final victory cannot, be measured…however, I am convinced that the expenditure of men and money in wielding the spoken and written word was an importable contributing factor in undermining the enemy’s will to resist and supporting the fighting morale of our potential Allies in the occupied countries'.
This total war was not confined to Europe, but reached across the world into Asia. British Online Archives has published a report on the perceived effectiveness of psychological warfare in the Far East. Guerrilla tactics were used by Allied forces in Asia to break down the morale of Japanese troops, frighten collaborators, and to raise the morale of resistance elements in occupied areas. One such tactic used in Burma was to set up loud speakers within a few hundred yards of the Japanese bunkers and send out a programme of impromptu speeches, gramophone records, and so on. As in the European theatre of war, the allied powers in Asia also printed and distributed surrender tickets, these guaranteed safe passage to the holder if they lay down their arms and surrendered to Allied forces. Although it can be difficult to examine the effectiveness of propaganda, one of the ways historians can assess the success of these tactics is by considering how many Japanese who surrendered carried these tickets. The document below suggests that it is noteworthy, that ‘although the totals of Japanese troops surrendering have not been considerable, in practically every case during the last campaign…they came bearing “surrender tickets” distributed by the I.F.B.Us’.
British Online Archives. Secrecy, Sabotage, and Aiding the Resistance: How Anglo-American Cooperation Shaped World War II.
James A.C. Brown, a Scottish psychiatrist, summed up the Second World War experience with the observation that "Propaganda is successful only when directed at those who are willing to listen, absorb the information, and if possible, act on it, and this happens only when the other side is in a condition of lowered morale and is already losing the campaign." Propaganda was at its most effective when the enemy were already becoming disillusioned. In the latter stages of the war, successful propaganda campaigns focused on: delivering ‘safe conduct’ passes to enemy soldiers who wanted to surrender; instructing soldiers on how to stimulate an illness ‘Better a few days illness than be dead all your life’; the importance of the individual and family ties; and how best to sabotage from within. During the Second World War airborne leaflet propaganda had grown from an enterprising novelty, to a major weapon of war showing measurable results.
The dissemination of airborne leaflet propaganda did not end with the peace following VE and V-J Day. The perceived success of propaganda in influencing the 'hearts and minds' led to US forces continuing to use this tactic during the war in Vietnam. The New York Times stated in 1971, during the withdrawal of US troops from Vietnam, that ‘the United States Army has printed…6,245,200,000 propaganda leaflets for air drops in Indochina’. This is an almost inconceivable amount of printed propaganda material, and emphasises the importance placed on this tactic. An army catalogue describes leaflets as very effective in ‘changing morale, reducing combat, encouraging defection, deceiving, creating unity or disunity, and informing local populations’. Often leaflet drops were carried out before airstrikes warning local populations of the destruction to come. However, the success of the US leaflet drop operation is debated. The Times article goes on to suggest that ‘the country has been so saturated with [leaflets] that throughout South Vietnam the leaflets can be seen performing several functions. The Vietnamese use them to wrap food, or in local restaurants they are convenient for wiping chopsticks or spoons. In the poorer huts, the leaflets are often used as wall paper to block holes’. Too much propaganda material being dropped into an area can cause the material to loose it’s effect as a propaganda tool.
As the Parisians first did in 1870, a modern form of airborne warfare is that of the balloon propaganda drop. This tactic has been used countless times over the past 150 years, one of the most lasting episodes in the public conscious is that of Korea. Frank Pace, then United States Secretary of the Army, strongly endorsed psychological operations, encouraging his men to “bury the enemy with paper”.[20.5] Equally, leaflets were produced by the North Korean Army and the Communist Chinese forces targeting UN troops and South Korean civilians. [20.5] However, interestingly this Propaganda campaign did not stop with the creation of the independent countries of North Korea and South Korea along the 38th parallel in 1953. Since then balloons have been sent, and known to travel for thousands of miles across the border. According to Alex Gladstein, Chief Strategy Officer at Human Rights Foundation (HRF), these balloon deliveries are very effective. When we think of a traditional balloon drop, we think of strongly worded propaganda leaflets. Indeed, this is the North Korean Governments preferred psychological weapon of choice. However, Gladstein argues that these leaflets have a minimal effect because they are not usually picked up by many people. Leaflets are mistrusted because they come from the source of hostile propaganda. Recently North Korean state-run media has warned people not to read propaganda leaflets sent via balloon, saying they could be carrying coronavirus. Gladstein runs the organisation Flash Drives for Freedom in South Korea, he sends footage, documentaries, and TV shows to North Korea via balloons. As well as flash drives, all manner of enticing, and sometimes bizarre, gifts are attached to balloons, including the vastly popular Choco Pie biscuits. Prof Andrei Lankov of Kookmin University in Seoul argues that treats have huge propaganda value, "Choco Pies are actually the best thing to send… when North Koreans see high-quality consumer goods produced overseas, they begin to understand that their economic system doesn't really deliver". The dispatching of propaganda leaflets and balloon deliveries has emerged as a new flashpoint between the two Koreas, North Korea calling it a provocation, and threatening retaliation. South Korea have responded by introducing a controversial new law banning individuals from sending propaganda via balloon over the border. However, in reality, this law is not easy to enforce and the use of balloon propaganda is still championed as an effective tool against the North Korean authoritarian regime. 
South Korean balloons carrying propaganda material across the 38th parallel.
The idea of using sound to disrupt an enemy has a long history, however, during the second world war using sound as a weapon really came into its own. Germany’s Stuka Ju-87, a dive-bomber fitted with a siren and dubbed the ‘Jerico Trumpet’, became the propaganda symbol of German air power. As technology has developed, so have the tactics employed in sonic psychological warfare. It is also a tactic that has been used intermittently in Korea since 1962, South Korean speakers blasted news reports and K-POP through the demilitarised zone, North Korean speakers broadcast critical reports back. In 2004 broadcasts were stopped as part of a North-South deal, however, they were briefly reinstated between 2015 and 2018, after which South Korea finally stopped broadcasting propaganda via loudspeakers. The effectiveness of sonic psychological warfare is debatable, South Korean President Park Geun-hye argued that the ‘truth is the most powerful weapon toward a totalitarian regieme’, and if you ‘listen to the accounts of North Korean defectors, the soldiers who were placed on the front line, they said at first they didn't believe the propaganda broadcasts, but later they did believe it, and that was the reason for them to come to South Korea’. Sonic warfare is not unique to this dispute, in 1967, as the Cold War threatened to heat up, the government in Taiwan built 30-foot-tall loudspeakers to blast anti-Communist propaganda across the few miles of sea separating Kinmen Island in Taiwan to the Chinese mainland. This ambitious project, known as the Beishan Broadcasting Wall projected its broadcast up to a range of 15 miles. The communist government in China staged a counterattack blasting their own nationalistic messages back. Taiwanese local resident Ling Ma-teng recalled the ‘mental exhaustion’ of residents living alongside this sonic warfare. “Back then the deafeningly loud sounds that came from the broadcast wall were looping around the clock non-stop,” says Ada Yang Kai-ting, who has collected the memories of local islanders during her research. The debate surrounding the morality and effectiveness of sonic warfare continues, however, it remains a key instrument in psychological warfare.
Beishan Broadcasting Wall in Jinning Township, Kinmen.
The evolution of psychological warfare over the last century and a half has given warring factions unprecedented access over enemy territories. Prior to this, the battle for hearts and minds was confined within the public sphere of an occupied territory. The advent of the mass printing press, the advancement of military aviation, and ultimately the technological revolution, mean that airborne propaganda has an ever-more far-reaching effect as a mode of psychological warfare.
For further study into the British Government’s information and propaganda released by the Ministry of Information and Central Office of Information between 1939 and 2009, please see BOA’s latest collection: https://microform.digital/boa/collections/100/british-government-information-and-propaganda-1939-2009.
 H. M. Baus & W. B. Ross. (1968). Politics Battle Plan, p.336.
 Loving, M. (2011) Bullets and Balloons: French airmail during the Siege of Paris. Franconian Press.
 Collier, B. (1974) A History of Air Power, p.12.
 Buckley, J. (2006) Air Power in the Age of Total War.
 Taylor, P.M. (1999) British Propaganda in the 20th Century.
 Simons, P. (2017) "A new weapon to spread propaganda leaflets: the balloon". The Times.
 Le Courrier de l'Air ?
 Oyen. O & De Fleur, M.L. (1953) "The Spatial Diffusion of an Airborne Leaflet Message" The University of Chicago Press, p.144.
 Rickards, M & Du Boscq, B. (2000) "Aerial Leaflet". The Encyclopedia of Ephemera, p.10.
 Erdmann, J. M. (1962). "The Monroe Leaflet Bomb Its Evolution And Significance." The Air Power Historian, 9(2), 101–128. http://www.jstor.org/stable/44512713
 British Online Archives, https://microform.digital/boa/documents/3035/selected-ussbs-source-documents, p.434
 Erdmann, J. M. "The Monroe Leaflet Bomb", p.101–128.
 Rickards, M & Du Boscq, B. The Encyclopedia of Ephemera, p.10.
 British Online Archives, https://microform.digital/boa/documents/11037/british-activities-past-and-planned-with-a-report-following-the-fall-of-singapore-1941-1945, pg.27.
 Ibid, p.28.
 Ibid, p.28.
 Rickards, M & Du Boscq, B. The Encyclopedia of Ephemera. p,11.
 Emerson, G. (1971) "U.S. Used Billions of Leaflets in Indochina War". New York Times.
 Dell, M & Querubin, P. (2017) Nation Building through Foreign Intervention: Evidence from Discontinuities in Military Strategies, https://scholar.harvard.edu/files/dell/files/vietnam_war.pdf, p.7
 Simons, P. (2017) "A new weapon to spread propaganda leaflets: the balloon". The Times.
[20b] Pease, S.E. (1992) “Psywar: Psychological Warfare in Korea, 1950-1953,” Harrisburg: Stackpole Bucks, p. 17
 "North Korea says propaganda leaflets sent from South could carry coronavirus". The Guardian. https://www.theguardian.com/world/2021/may/07/north-korea-says-propaganda-leaflets-sent-from-south-could-carry-coronavirus?CMP=Share_AndroidApp_Other
 Tan,Y. (2018) "North and South Korea: The petty side of diplomacy". BBC News. https://www.bbc.co.uk/news/world-asia-43806930
 Evans, S. (2014) "South Koreans wage chocolate propaganda war with chocolate pie". BBC News. https://www.bbc.co.uk/news/world-asia-29751650
 "Flash Drives for Freedom", https://flashdrivesforfreedom.org/ [Accessed: 2nd December 2021]
 "South Korea turns off loudspeaker broadcasts into North". (2018) BBC News. https://www.bbc.co.uk/news/world-asia-43861161 [Accessed: 2nd December 2021]
 Hu, E. "Responding To Nuclear Test, S. Korea Cranks Up The K-Pop". NPR News. https://www.npr.org/sections/parallels/2016/01/13/462853390/responding-to-nuclear-test-s-korea-cranks-up-the-k-pop?t=1638458597047 [Accessed: 2nd December 2021]
 Chow, V. (2018) "Beishan Broadcast Wall: Taiwan’s eerie sonic weapon". BBC Culture. https://www.bbc.com/culture/article/20180924-beishan-broadcast-wall-taiwans-eerie-sonic-weapon?referer=https%3A%2F%2Fen.wikipedia.org%2F [Accessed: 2nd December 2021]
Baus, H.M. & Ross, W. B. (1968). Politics Battle Plan
Buckley, J. (2006) Air Power in the Age of Total War
Chow, V. (2018) "Beishan Broadcast Wall: Taiwan’s eerie sonic weapon". BBC Culture. https://www.bbc.com/culture/article/20180924-beishan-broadcast-wall-taiwans-eerie-sonic-weapon?referer=https%3A%2F%2Fen.wikipedia.org%2F
Collier, B. (1974) A History of Air Power
Dell, M & Querubin, P. (2017) Nation Building through Foreign Intervention: Evidence from Discontinuities in Military Strategies, https://scholar.harvard.edu/files/dell/files/vietnam_war.pdf
Emerson, G. (1971) "U.S. Used Billions of Leaflets in Indochina War". New York Times.
Erdmann, J. M. (1962). "The Monroe Leaflet Bomb Its Evolution And Significance." The Air Power Historian, 9(2)
Evans, S. (2014) "South Koreans wage chocolate propaganda war with chocolate pie". BBC News. https://www.bbc.co.uk/news/world-asia-29751650
"Flash Drives for Freedom", https://flashdrivesforfreedom.org/
Hu, E. "Responding To Nuclear Test, S. Korea Cranks Up The K-Pop". NPR News.
Loving, M. (2011) Bullets and Balloons: French airmail during the Siege of Paris. Franconian Press.
"North Korea says propaganda leaflets sent from South could carry coronavirus". The Guardian. https://www.theguardian.com/world/2021/may/07/north-korea-says-propaganda-leaflets-sent-from-south-could-carry-coronavirus?CMP=Share_AndroidApp_Other
Oyen. O & De Fleur, M.L. (1953) "The Spatial Diffusion of an Airborne Leaflet Message" The University of Chicago Press
Pease, S.E. (1992) “Psywar: Psychological Warfare in Korea, 1950-1953,” Harrisburg: Stackpole Bucks
Rickards, M & Du Boscq, B. (2000) "Aerial Leaflet". The Encyclopedia of Ephemera
Simons, P. (2017) "A new weapon to spread propaganda leaflets: the balloon". The Times.
"South Korea turns off loudspeaker broadcasts into North". (2018) BBC News. https://www.bbc.co.uk/news/world-asia-43861161
Tan,Y. (2018) "North and South Korea: The petty side of diplomacy". BBC News. https://www.bbc.co.uk/news/world-asia-43806930
Taylor, P.M. (1999) British Propaganda in the 20th Century