Why was Britain’s military so weak during the 1930s & early WW II?

World War II started on September 1, 1939, with the German invasion of Poland. And on September 3 1939 both France and Great Britain declared war on Germany.

But even though both France and Great Britain had declared war they didn`t attack the weakly defended western borders of Germany. And when Germany attacked in 1940 French and British troops were unable to stop the German invasion.

But what were the reasons for the weakness of Great Britain’s military?

Great Britain’s massive debts from WW I made it necessary to cut back on military spending and the ten-year rule declared that there would not be a bigger war until 1935. So the army was massively reduced and the further development of new weapons like tanks was neglected.

Let`s find out more!

Why was Great Britain`s military so weak – Reasons

There were multiple reasons why the British military had to change after the end of World War I.

The following paragraphs will present an overview of the events and decisions of the 1920s and 1930s that led to the weakness of the British military during the 1930s and early WW II.

Cutting of the military budget due to debt from World War I

Great Britain was on the winning side of World War I. And as such, it was one of the recipients of the war reparations defeated Germany had to pay.

And Great Britain was in serious need of these reparations but due to the weakness of its economy, it became clear that Germany would not be able to deliver the number of Reparations the winners of World War I expected.

And Germany also couldn`t deliver them as fast as the victorious powers wanted. The reasons for that are quite interesting but a story for another time.

It actually took Germany until 2010 to fully pay off the reparations of World War I.

So after 1918 Great Britain could not rely on german reparations for a fast income.

And that was a problem since 2/3 of the British expenses for World War I were financed through debt. (The USA was one of the biggest lenders)

Or in other words: After World War I victorious Great Britain had to save money. And one of the obvious solutions was to cut back on the spendings for the army, navy, and airforce.

Since 1922 the military budget of Great Britain had sunk every year and in 1933, the year Hitler became Chancellor in Germany, the military budget only made up 2.5% of the British gross national product.

Now the cuts of the budget were not equally distributed among the army, navy, and airforce.

The budget of Royal Navy and Royal Airforce – almost untouched

Traditionally the Royal Navy had a strong stance in Great Britain.

Not only did the Admiralty claim that in order to be able to defend the British island the British Navy had to be stronger than its contestants, but the Royal Navy was also important for connecting Great Britain with its Empire overseas.

The Royal Airforce argued similarly. Only if the British airforce was stronger than any other airforce it would be able to ensure the defense of Great Britain.

By the way, the focus was put on building up the number of bombers.

The reason for that was the idea that a war could be won by bombarding the enemy. The idea of Air defense wasn`t really given too much thought.

That was the reason why Great Britain didn`t really increase its air force. Since Germany didn`t have any Air force until 1933 the only serious opponent during the mid-1920s when it came to the airforce was France. And Great Britain didn`t want to armor up against France.

Now that didn`t mean that Great Britain did not make emergency plans for a military confrontation with France.

Actually, the British plans of the early 1930s for the use of their airforce all dated back to 1923 and were tailored for a confrontation with France.

That in return led to a few big problems during the early weeks of World War II.

Since these plans were all designed for the case of a military conflict between Great Britain and France the airplanes were constructed for that purpose.

In 1939 only 15% of the British bombers had enough fuel capacity to reach German territory. None of them could have reached Berlin! And that didn’t change until shortly before WW II.

More on that in the last paragraph of the article.

Now you might ask why in 1939/40 the British military didn’t just focus on defending the airfields in France and Belgium with their army and then operate from there.

The reason is that since neither the Navy nor the Airforce had to endure massive budget cuts the Army had to carry most of the savings.

The budget of the British army – massively cut

After World War I the expenses for the army were massively cut. And after the introduction of the ten-year rule, more on that in the next paragraph, the army got even less money.

Now that had several reasons.

For once the money had to be saved somewhere. And since the Navy and Airforce had made a good case why their funding should not be cut the Army was the part of the military that had to make up for that.

The next reason was that after World War I the British army didn`t have a lot to do.

After WW I the tasks of the British army were to secure the airbases in the Middle East and to be ready to end possible rebellions either in the Colonies or in Britain.

Because of the ten-year rule that we are going to take a look at next the threat of another big war was seen as negligible.

That by the way did not only lead to the drastic reduction of soldiers but also to the stop of developing and improving new weapons like tanks.

Between the World Wars, the British army was basically a heavily reduced army that was designed for use in the British colonies, not on the European continent!

That kind of deficient preparation for a land-based war was one of the reasons why Great Britain (and France) did not invade Germany’s less protected western regions in 1939/40 although they had the numerical advantage over the german troops.

More on that and the so-called „Phoney War“ of 1939/40 in my article here.

The question of if Great Britain could catch up on its residue will be debated down below at the end of the article.

The Ten-year rule

A lot of the lack of British preparation for another big war can be attributed to the so-called ten-year rule.

But what was the ten-year rule?

The ten-year rule was the official British assessment that no bigger war would occur within the next 10 years. It was first established in 1919 and was regularly extended until the early 1930s.

For us looking back on the 1920s and 1930s, the assumption that no bigger war would occur in the next 10 years seems pretty ridiculous.

But we have to realize that the knowledge we have today can`t really be used to evaluate if the decisions that were made in the 1920s were naive.

Because during the middle of the 1920s the situation looked really good. Not only was that the time of the roaring twenties, but there was also no acute threat situation.

World War I was long over. A demilitarized Germany only had an army of 100.000 soldiers, no Airforce, no Tanks, no heavy artillery, and only a small navy without submarines and battleships.

Russia did not only have a weak military but was also mostly occupied with inner conflicts. Japan and Great Britain were connected in friendship and neither France nor the USA was a threat (although the British Press claimed that both had a certain interest in areas of the British Empire.

Even the hereditary enemies Germany and France started to get closer. That process was owed to the German Foreign Minister Gustav Stresemann and his French counterpart Aristide Briand (they would receive the Nobel Peace Price in 1926).

And the League of Nations, established after World War I, planned to organize a global disarmament conference, more on that in the next paragraph.

So to sum it up:

During the 1920s Great Britain had every reason to estimate that there would not be a bigger war in the next decade. It wasn`t until the Japanese expansion in the Far East (since 1931) and the rearmament policies of Hitler that the situation changed.

Before that, the international spirit favored disarmament over armament.

The International spirit favors disarmament

The already mentioned international spirit for disarmament was crowned by the disarmament conference that was held between February 1932 and June 1934.

The idea that fewer weapons would prevent wars was not only common in Great Britain where all political parties agreed on the idea of disarmament.

(Only the military leaders had a different idea. According to them, only trustworthy nations should keep their weapons while all others should give up arms. Needless to say that the British high-ranking officers saw Great Britain as trustworthy enough to keep its weapons…)

The disarmament conference ended without a real solution in 1935 after Germany had officially started to re-arm its army again. After that, disarmament of the other nations no longer seemed wise and measurements were taken.

More on the British measurements in the last paragraph down below.

The end of the ten-year rule

In March of 1932, only one month after the start of the international disarmament conference the British government stepped away from the ten-year rule and ordered the military to draw up proposals on how to eliminate the biggest deficits of the British armament.

But although the National Government thought about armament it still could not step away from its politic of saving for which it had been voted in the first place.

Because of that, it was widely expected that the rearmament would be a slow process. In 1932 the conservative Chancellor of the Exchequer Neville Chamberlain would set the lowest military budget of the entire time during the World Wars.

It took the military leader entire two years to come up with their proposals.

In 1934 the leaders of the Royal Navy, the Royal Airforce, and the Army presented their plans for rearmament. That plan did no longer see Japan (which had been expanding since 1931 in the Far East) but Germany as the major threat.

That switch was closely connected to a comment that Hitler had made in the spring of 1935.

In the spring of 1935, Hitler claimed that the German Airforce (that had been built since 1933) was now superior to the British Royal Air Force. That led Stanley Baldwin to demand that the Royal Air Force must be made at least equal to the German Luftwaffe.

Baldwins’ demand is a good point to speak about the British re-armament after 1935.

The British re-armament since the mid-1930s

After 1935 the British rearmament was taken seriously again.

On March 4, 1935, the British government published the „Statement relating to Defense“ in which the renunciation of the concept of international peace through disarmament was announced.

From now on Great Britain planned to return to the concept of national security through armament.

Now the Statement relating to Defense didn`t have immediate consequences in Great Britain. But it had consequences in Germany.

Hitler took the British Statement relating to the defense of March 4, 1935, as a justification to bring back the conscription on March 16, 1935.

In 1936 the Royal Air Force was officially divided into a bomber command and a fighter command. But the focus was still put on the bomber command.

On March 7, 1936, the German army marched into the demilitarized Rhineland. Now that action clearly inflicted the rules of the Locarno treaties. But in terms of actual significance, it was nothing more than a symbolic gesture since Hitler had ordered his generals to withdraw at the slightest sign of resistance.

And yet Great Britain, which was tasked with guaranteeing the fulfillment of the Locarno treaties, would have had an obligation to at least do something.

But apart from imposing economic sanctions, Great Britain didn`t do a lot.

Prime minister Stanley Baldwin even publicly announced that Great Britain just didn`t have the soldiers necessary to intervene with the German occupation of the previously demilitarized Rhineland.

After that Great Britain realized that it had to put more money into armaments. Because of that a tax, the National Defense Contribution, was introduced by Neville Chamberlain in April of 1937.

The Royal Air Force actually profited the most of that contribution and was able to draw even to Germany until the start of World War II.

More on the start of World War II and the surprising actions Germany took to not appear as the aggressor here in my article.

But although the re-armament was going pretty well there was one main problem.

And that was a lack of coordination between the civil government and the military.

I have already talked about how due to the lack of new plans during the 1930s the war preparations of the Airforce were still tailored toward a conflict with France.

But let`s now investigate the question if even with the process of re-armament going Great Britain was well prepared for World War II.

Was Great Britain well prepared for WW II?

As already mentioned above. Until 1939 most of the newly constructed British bombers were not able to reach Berlin and only 15% could reach any german territory.

Now the idea was probably that in case of need the airplanes could start from airbases in France and Belgium to reach german territories and Berlin.

But one of the consequences of the massively reduced army was that the army was too small to defend these airbases against a German attack.

So in other words.

Even though Great Britain had started the process of re-armament after the spring of 1935 and was able to close the residue on Germany its massively reduced army made the British land-based support of France in 1939/40 susceptible.

By the way. The events that I just presented in the post were also a major reason why Great Britain and France did not invade Germany’s western territories while the german army was fighting in Poland.

Do you want to find out more on why Great Britain and France did not invade Germany in 1939 even though they had the numeric advantage of 85 french against 34 german divisions?

You can find the answer in my article here.

Take care of yourself because you deserve it. You really do.

Until next time

Yours truly

Luke Reitzer


P. Clarke: Hope and Glory, Britain 1900-1990 (London 1996).

A. Marwick: A History of the Modern British Isles, 1914-1999 Circumstances, Events and Outcomes (Oxford/Malden 2000).

P. Dewey: War and Progress, Britain 1914-1945 (London/New York 1997).