Diplomacy Outside the League: Locarno and Kellogg-Briand
A New Mood in Europe
By 1924, the worst of the post-war crisis was passing. Germany’s 1923 hyperinflation had been stabilised by Gustav Stresemann’s government with the new Rentenmark; the Dawes Plan of 1924 restructured reparations and brought American loans; and France had begun to withdraw its troops from the Ruhr, completing this in 1925. The result was a brief period of European optimism, often called the ‘Locarno spirit’. The 1920s reached their high-water mark of internationalism not through the League itself but through diplomacy outside it — the Locarno treaties of 1925 and the Kellogg-Briand Pact of 1928.
The Locarno treaties were signed in October 1925 by foreign ministers Gustav Stresemann (Germany), Aristide Briand (France) and Austen Chamberlain (Britain). Germany, France and Belgium voluntarily guaranteed each other’s western borders, with Britain and Italy as guarantors.
Gustav Stresemann and Reconciliation
Stresemann was the leading figure of Weimar foreign policy, serving as Chancellor briefly in 1923 and as Foreign Minister from 1923 until his death in 1929. His policy was reconciliation diplomacy — cooperation with the western powers to revise the Treaty of Versailles peacefully. He calculated that confrontation would only deepen Germany’s isolation, while patient negotiation could relax reparations, end the occupation of the Ruhr, and bring Germany back into the great-power club.
It would be wrong, however, to read Stresemann as an idealistic peace-maker. His private letters show a clear-eyed strategist who wanted to recover German territory, restore German military power and undo Versailles — just by negotiation rather than force. The reconciliation was tactical. He pursued three concrete objectives: ending the French and Belgian occupation of the Ruhr, lifting the burden of reparations, and bringing Germany back into the great-power club through admission to the League of Nations. He used his fluent diplomatic style to build personal trust with Briand and Austen Chamberlain, while quietly continuing secret rearmament cooperation with the Soviet Union under the 1922 Treaty of Rapallo. None of this contradicted his public reconciliation policy — the two ran in parallel. Between 1924 and 1929 he successfully repositioned Germany from outlaw state to respected partner, achieving more by negotiation than the German army had achieved on the battlefield in the four years of war.
The Locarno Treaties, October 1925
Negotiations began in early 1925 in the Swiss town of Locarno. The central agreement was a western frontier guarantee: Germany, France and Belgium voluntarily accepted their existing borders as final. Britain and Italy guaranteed to act if any of the three were attacked. Germany also signed arbitration treaties with Poland and Czechoslovakia — but, crucially, did not guarantee its eastern frontiers as final.
This omission was deliberate and would matter enormously. By accepting the western borders but leaving the eastern ones open, Germany signalled that the Polish Corridor, Danzig and the Sudetenland were still subject to revision. Locarno was widely celebrated — Austen Chamberlain won the Nobel Peace Prize for 1925, and Stresemann and Briand won it for 1926 — but it built in the very ambiguity that Hitler would exploit.
Three immediate consequences flowed from Locarno. First, in September 1926 Germany joined the League of Nations as a permanent Council member — rehabilitation completed. Second, French troops withdrew from the Rhineland zones earlier than the treaty required, the last departing in 1930 (five years ahead of schedule). Third, the ‘Locarno spirit’ encouraged broader optimism that brought the Young Plan (1929) further reducing reparations and the Kellogg-Briand Pact (1928) renouncing war. For four or five years, Europe felt as if it had turned a corner.
The Kellogg-Briand Pact, 1928
The pact was a French initiative that an American Secretary of State turned into something larger. Aristide Briand initially proposed a Franco-American agreement to outlaw war between the two countries — partly as insurance against German recovery. Frank B. Kellogg, the American Secretary of State, suggested expanding it to include all states. The result, signed in Paris on 27 August 1928 by 15 countries and eventually ratified by 62, was a public renunciation of war as an instrument of national policy.
In effect, signatories pledged to settle disputes peacefully and never start a war of aggression. The pact had no enforcement mechanism — no penalties, no court, no army. Critics dismissed it from the start as an empty gesture. But the symbolism mattered. For the first time in history, almost every major state had publicly committed to outlawing war, providing the legal foundation that would later allow the prosecution of aggressive war as a crime at the Nuremberg trials in 1945-46.
Beneath the celebrations, three serious limits should be noted. First, eastern Europe was not protected: Germany did not commit to its frontiers with Poland and Czechoslovakia. Second, the agreement depended entirely on the personalities of the three foreign ministers; when Stresemann died in October 1929 and economic crisis followed in 1930, the Locarno spirit dissolved within months. Third, the agreement was made outside the League of Nations rather than through it, which subtly weakened the League’s status as the central body for European security — great powers preferred bilateral or multilateral deals to the unanimity-bound Council.
Locarno guaranteed only Germany’s western borders. Its eastern frontiers with Poland and Czechoslovakia were left open to revision. This deliberate ambiguity allowed Hitler to use the Sudetenland and the Polish Corridor as flashpoints in 1938-39.