When Demilitarization Commitments Ignored: Violation Facilitated Germany's
Invasion of France
Dr. Aaron Lerner 28 December 2025

Step-by-Step Explanation of the French Withdrawal from the Rhineland in 1930
and Subsequent Events
Background: Demilitarization of the Rhineland under the Treaty of Versailles
(1919)

After World War I, the Treaty of Versailles imposed strict limitations on
Germany to prevent renewed aggression. The Rhineland-defined as the
territory west of the Rhine River and a strip extending 50 kilometers east
of the Rhine-was designated a demilitarized zone.

The relevant provisions were:

Article 42:
"Germany is forbidden to maintain or construct any fortifications either on
the left bank of the Rhine or on the right bank to the west of a line drawn
50 kilometers to the east of the Rhine."

Article 43:
"In the area defined above, the maintenance and assembly of armed forces,
either permanently or temporarily, and military manoeuvres of any kind, as
well as the upkeep of all permanent works for mobilization, are in the same
way forbidden."

Article 44:
Any violation of Articles 42 or 43 would be regarded as a hostile act
against the treaty powers and as an act calculated to disturb the peace of
the world.

These provisions created a security buffer intended to protect France and
Belgium from renewed German attack.

To guarantee compliance, the treaty also provided for Allied military
occupation of the Rhineland. Under Articles 428-432, occupation was to last
15 years from the entry into force of the treaty, with withdrawals in three
stages (after 5, 10, and 15 years), conditional on German compliance.

The Locarno Treaties (1925): Reconfirmation and Guarantee of
Demilitarization

In 1925, Germany (under Foreign Minister Gustav Stresemann), France,
Belgium, Britain, and Italy signed the Locarno Treaties. The key agreement
was the Treaty of Mutual Guarantee (Rhineland Pact).

Under this treaty:

Germany, France, and Belgium mutually recognized the inviolability of their
western borders as fixed by Versailles.

Britain and Italy acted as guarantor powers, pledging to assist any victim
of aggression.

Crucially, the parties explicitly guaranteed "the observance of the
stipulations of Articles 42 and 43 of the Treaty of Versailles concerning
the demilitarised zone."

Locarno did not replace Versailles. Rather, it reconfirmed and guaranteed
the existing demilitarization regime within a new diplomatic framework. It
was politically significant because Germany accepted these obligations
voluntarily, unlike the imposed terms of 1919.

French and Allied Withdrawal from the Rhineland (1930)

Although occupation was originally scheduled to continue until the
mid-1930s, events accelerated its end:

In 1929, the Young Plan restructured Germany's reparations, reducing annual
payments and extending the payment period.

As part of the Hague agreements linked to the Young Plan, the Allied powers
agreed to accelerate evacuation of the Rhineland.

France, initially reluctant, accepted early withdrawal in exchange for
financial and political concessions.

The final Allied troops-primarily French-completed their withdrawal on 30
June 1930, five years earlier than originally planned.

Importantly, the end of occupation did not terminate demilitarization. The
legal obligation to keep the Rhineland free of German troops and
fortifications remained fully in force under Articles 42-44 of Versailles
and was reaffirmed by Locarno.

Germany's Violation: Remilitarization of the Rhineland (1936)

Under Adolf Hitler, Germany openly violated these obligations.

On 7 March 1936, Germany sent 19 battalions (approximately 20,000-30,000
troops) into the demilitarized Rhineland.

Hitler claimed that the Franco-Soviet Mutual Assistance Pact (1935)
constituted a threat to Germany and rendered Locarno void.

This action directly violated:

Article 43 of the Treaty of Versailles, which forbade the presence or
assembly of armed forces in the demilitarized zone.

Article 42, once Germany subsequently began constructing fortifications.

The Locarno Rhineland Pact, which guaranteed observance of those Versailles
provisions.

Britain and France protested diplomatically but took no military action. The
matter was referred to the League of Nations, but no enforcement measures
followed. Hitler had instructed his forces to withdraw if met with
resistance; none came. The episode emboldened further German expansion.

Role of Rhineland Remilitarization in the German Victory over France (1940)

The remilitarization of the Rhineland was a critical enabler-though not the
sole cause-of Germany's rapid victory over France in May-June 1940.

Its strategic consequences included:

Elimination of France's primary security buffer. The demilitarized Rhineland
had allowed France to threaten rapid entry into western Germany in the event
of German aggression. Remilitarization removed this deterrent.

Construction of the Westwall (Siegfried Line). After 1936, Germany built
extensive fortifications along the western frontier, opposite the French
Maginot Line. This reduced German fear of a French counteroffensive.

Greater freedom of force concentration. With the western frontier secured,
Germany could allocate forces with greater confidence to offensive
operations.

Strategic risk acceptance in 1940. During the Battle of France, German
forces bypassed the Maginot Line by advancing through Belgium and the
Ardennes. The existence of the Westwall helped reassure German planners that
France could not easily strike into Germany during the campaign.

The result was the rapid encirclement and defeat of Allied forces in
northern France and Belgium, culminating in the evacuation at Dunkirk and
the fall of France within six weeks.

Summary

The 1930 Allied withdrawal ended military occupation but did not end
demilitarization, which remained guaranteed under both the Treaty of
Versailles and the Locarno Treaties. Germany's 1936 remilitarization was a
clear treaty violation that removed France's principal security safeguard,
enabled German western fortifications, and altered the strategic balance in
Europe. This unopposed breach played a significant role in creating the
conditions that made Germany's 1940 Blitzkrieg against France possible and
devastatingly effective.
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