What do you do when diplomacy fails? Diplomacy attempts such as peace treaties, sanctions, and appeasement during the Interwar Period (1919-39) were ineffective in preventing World War II (WWII), as exemplified by the Treaty of Versailles, the Franco-Soviet Treaty of Mutual Assistance, the Anglo-German Naval Agreement, the Munich Agreement, and the Molotov-Ribbentrop Pact. These treaties failed to stop Hitler’s quest for power by failing to hold him accountable, which in turn enabled him to gain popular support in Germany, build military power, and invade surrounding countries with little resistance. Even what some may argue was the most hopeful and idealistic peace treaty of the twentieth century, the Kellogg-Briand Pact, was ineffective in preventing WWII.

The Treaty of Versailles, signed in 1919 by the Allied Powers (Britain, France, and Russia) and Germany, officially ended World War I (WWI) and outlined the terms of Germany’s surrender. The treaty reduced German territory by 10% and granted it primarily to Belgium, Czechoslovakia, Poland, and France; required Germany to pay 33 billion Dollars (in 1919 dollars) in reparations to the Allied Powers; and forced Germany to “accep[t] the responsibility [...] for causing all the loss and damage” of WW1 (1). To limit Germany’s military power, the treaty restricted the size of the German army to 100,000 people; capped the naval force to 15,000 people, six battleships, and no submarines; banned the Luftwaffe (German air force); prohibited arms manufacturing; and demilitarized the German Rhineland (which bordered France, Belgium, and the Netherlands). Allied troops were stationed in the Rhineland in an effort to ensure Germany’s compliance (2). The treaty aimed to bolster the Allies economically while weakening Germany’s power and ability to wage war. Although the terms of the treaty satisfied European Allied Powers, the American government favored a less harsh agreement aligning with Woodrow Wilson’s Fourteen Points - his vision for a postwar world, which included free and equal trade (3). The punitive terms enraged Germany, especially because they did not conform to the Armistice of 11 November 1918, which Germany had previously agreed to; notably, this armistice did not include reparations. The Treaty of Versailles was economically devastating for Germany. As reparations exacerbated Germany’s already weakened economy, Germany printed more money, causing steep inflation. For example, before WWI, one United States (U.S.) Dollar was worth four German Marks; by 1923, one Dollar equaled one trillion Marks (4). As the quality of life in Germany declined, citizens resented the government’s inefficacy in resolving economic crises (5). Hitler denounced the unpopular and dysfunctional government to gain popularity with the suffering German citizens (6). The hyperinflation resulting from the Treaty of Versailles fostered resentment of the Weimar government which enabled the Nazi Party and Hitler to gain political power.

Even pacts that Germany was not party to, such as the May 1935 Franco-Soviet Treaty of Mutual Assistance, ultimately bolstered Hitler’s regime. In 1933, Germany left the League of Nations after being denied the right to remilitarize, alarming other European countries. The French proposed to the Soviet Union that they create a pact to exchange resources and military aid in case of German invasion - if Germany expanded west into France, the Soviet Union would invade Germany from the East and vice versa. The pact aimed to deter Hitler from expanding into other countries with the threat of war on both its Western and Eastern fronts (7). In March 1935, Hitler began conscripting German citizens to rebuild and grow his army in direct violation of the Treaty of Versailles, causing French cabinet members to advocate for the finalization of the Franco-Soviet Treaty (8). Hitler described this attempt at containment as foreign aggression, allowing him to build political support through his speeches denouncing Russia (9). He marched German forces into the Rhineland, further violating the Treaty of Versailles (10). The Franco-Soviet Treaty failed in deterring Hitler from rearming; in fact, it encouraged him to remilitarize the Rhineland, escalating aggression by stationing troops along the French border. Furthermore, it helped Hitler engage in fearmongering to promote militarization and gain political support in Germany. Even though Hitler mobilizing troops was in direct violation of the Treaty of Versailles, the Allied Powers failed to impose sanctions in response.

Some treaties, like the June 1935 Anglo-German Naval Agreement, were orchestrated by Hitler under false pretenses to further his agenda. The Anglo-German Naval Agreement limited Germany’s naval capacity relative to Britain’s. Attempts to limit naval capacity across nations were first made at the 1932-1934 League of Nations Disarmament Conference; however, the Conference dissolved in June 1934 without reaching an agreement. During the conference, Germany gave Britain an ultimatum: if the negotiations did not give Germany military parity with other nations, Germany would violate the Treaty of Versailles by re-arming (11). When the Conference dissolved, Germany approached Britain to propose what became the Anglo-German Naval Agreement. On the surface, this agreement capped the size of the German navy at 35 percent of the British navy as measured in tonnage, but there were several significant exceptions that benefited Germany (12). For example, since this metric is measured in tonnage, the number of German submarines could equal that of the Royal Navy if Germany constructed a lighter fleet. Additionally, the German submarine fleet could equal that of the Royal Navy in the presence of “a situation arising which in [Germany’s] opinion makes it necessary for Germany to avail herself of her right to a percentage of submarine tonnage exceeding” the previously mandated levels (13). In other words, this agreement allowed Germany to declare an extenuating circumstance and use it as an excuse to build up to the total tonnage of the Royal Navy’s submarine fleet. This granted Germany a huge military advantage - Germany’s submarine fleet expanded twentyfold throughout the war (14). This was especially salient given Germany’s successful use of unrestricted submarine warfare during WWI - they sunk neutral cargo and passenger ships. Despite the fact that the Treaty of Versailles limited German naval expansion, Britain believed it was in its best interest to allow Germany to expand its navy provided that British naval superiority remained intact (15). Because France had been so vociferously against allowing Germany to rearm, Britain unilaterally entering the agreement to the exclusion of their allies created discord between the Allied Powers (16). Britain ignored the wishes of their allies and the League of Nations in order to appease Hitler. However, the other Allied Powers took no action to counter Britain’s decision, which signaled to Hitler that the terms of the Treaty of Versailles were weakly enforced and could be violated without opposition. The agreement helped Hitler to expand his naval power while weakening alliances between his opponents.

At the September 1938 Munich Conference - the most desperate attempt in appeasing Germany - Britain, France, and Italy granted Hitler control of the German-speaking Sudetenland in Western Czechoslovakia. Earlier that year, Hitler annexed Austria, his home country, then set his sights on the Sudetenland in Western Czechoslovakia to further his goal of reuniting ethnic Germans under the German Reich. The Sudeten people wanted to join the German Reich, but the Czechoslovakian government was opposed. Before the Munich Conference, Hitler gave an ultimatum, demanding control of the Sudetenland to protect Czechoslovakia from violent annexation (17). If Hitler were to attack, another world war was very likely: Russia would be compelled to come to Czechoslovakia’s aid as mandated by the Czechoslovak–Soviet Treaty of Mutual Assistance (18), and France and Britain would also intervene pursuant to their obligations under the Locarno Pact (19). Thus, British Prime Minister Neville Chamberlain orchestrated the Munich Conference in an attempt to avert war (20). This culminated with the Allies forcing Czechoslovakia to let Germany annex the Sudetenland (21). Representatives from the Czech government were not allowed at the conference (22). The agreement pleased Chamberlain, who declared he had achieved “peace for our time” (23). The Sudetenland was especially key to Hitler’s mission because it contained Czechoslovakia’s natural resources, power stores, and military equipment. After Hitler occupied the Sudetenland and controlled these resources, the rest of Czechoslovakia became much more susceptible to invasion from Hitler (24). Although this pact may have slightly delayed WWII, the attempt at appeasement was unsuccessful. Conversely, the Munich Pact militarily empowered Hitler, granting him access to natural resources and military fortifications along Czechoslovakia’s border; controlling these, he easily invaded the rest of Czechoslovakia in March 1939. The Allied Powers failed to take action against Hitler, despite having treaty obligations to aid Czechoslovakia. Not even the conquest of Austria and Czechoslovakia satisfied Hitler; he invaded Poland in late 1939, catalyzing WWII.

Following Hitler’s invasion of Czechoslovakia, the Soviet Union was obligated to come to the Czech’s defense under the Czechoslovak–Soviet Treaty of Mutual Assistance, yet were reluctant to do so due to a weak military. The Molotov-Ribbentrop Pact of late August 1939 intended to delay war between Germany and the Soviet Union (25). This pact mandates that both countries “desist from any act of violence, any aggressive action, and any attack on each other, either individually or jointly with other powers” (26). Each country had motive to sign the pact; Stalin sought time to rebuild the Soviet Military without German threat, while Hitler aimed to invade and control Poland without intervention from the Soviet Union. Toward this end, the pact included “Secret [...] Protocol[s];” a significant one established German and Soviet spheres of influence in Eastern Europe (notably in Poland) (27). Historian Michael Lynch points out that “neither leader [Stalin and Hitler] truly trusted the other […] what they were buying was not peace but a delayed war” (28). Although short-lived, these two years of non-violence gave Stalin time to rebuild the Soviet military, while the pact ensured that Hitler could invade Poland without Soviet intervention. Hitler invaded Poland on September 1st, 1939. He anticipated French and British intervention pursuant to the Locarno Pact and the Anglo-Polish Alliance, respectively. Both came two days later when Britain and France declared war on Germany. Although this agreement temporarily maintained peace between Germany and the Soviet Union as intended, it also supported Hitler in achieving his military goals of expanding the German Reich. Knowing Stalin would not take military action from the East following the Molotov-Ribbentrop Pact, Hitler concentrated his troops in Western Germany (29). Thus, the pact gave Hitler the opportunity to effectively strengthen his forces. The pact also expedited Hitler’s invasion of Poland, which occurred just nine days later, because Hitler knew he would not face Soviet resistance. Not only did Hitler’s invasion of Poland precipitate WWII, but he unsurprisingly reneged the agreement when he invaded the Soviet Union 2 years later in June 1941.

Even more favorably viewed treaties, such as the 1928 Kellogg-Briand Pact, were ineffective in preventing WWII. The most hopeful of peace agreements, the Kellogg-Briand Pact was well-intentioned in its goal to outlaw war after the devastation of WWI and was widely accepted, garnering support from 47 countries (30). This agreement also mandated that international disputes could only be resolved peacefully and reflected public favor towards pacifism (31). However, the treaty lacked enforcement provisions; as such, the treaty did little to deter aggressors. For example, Japan invaded Manchuria in 1931, despite having signed the pact three years prior. Germany signed the pact but contravened it numerous times in the leadup to WWII (32). Despite having some positive long-term effects, such as later being the inspiration for the Nuremberg trials, the Kellogg-Briand pact failed to prevent violence, notably WWII and the Holocaust.

Despite aiming to foster peace, the Kellogg-Briand Pact was unsuccessful in preventing WWII. Subsequent attempts to appease, contain, or make peace with Germany leading up to WWII were ineffective and failed to hold Hitler accountable for his numerous transgressions. The agreements failed because Germany did not act in good faith or uphold the terms of the treaties, and the Allied Powers did a poor job of enforcing said terms. Not only did these agreements fail to help, they often empowered Hitler. Through the failure of these treaties, Hitler was able to build popular support for the Nazi regime, remilitarize the Rhineland, gain massive submarine power, and annex Czech military fortifications and natural resources, which fueled his later invasions of Czechoslovakia and Poland, catalyzing World War II.