On August 23, 1914, two momentous battles were fought in Europe.

The first, at Mons, was the first big engagement for the British Expeditionary Force.  Britain hadn’t fought a major battle on the Continent since Waterloo, and this was a test of the training and doctrine of the past 100 years.  Small compared to the French and German armies, the BEF relied on discipline and skill to overcome numerical deficiencies.  Mons has become a legend in British military history, as stories of the battle highlight British marksmanship and discipline.  However, even had the French not retreated from their flanks, the BEF probably wouldn’t have been able to hold against the German onslaught.  The retreat from Mons continued for weeks, and only ended when the Germans turned in front of Paris, precipitating the Battle of the Marne.

The other battle was the titanic clash that has become known as Tannenberg.  In this engagement, the Russian Second Army and the German Eighth Army met in Prussian territory as part of a Russian stab into Germany.  German forces on the Eastern Front were only supposed to hold the Russians until the French and British were crushed, but due to superior generalship, superior reconnaissance and intelligence work, and infighting between the Russian commanders, the Germans were able to concentrate their forces against the Russians and defeat them in detail.  The German commanders, Hindenburg and Ludendorff, made their reputations at Tannenberg, and were effectively running Germany by the end of the war.  The commander of the Russian Second Army, Samsonov, was so ashamed of his performance at Tannenberg that he committed suicide rather than face capture or facing the Tsar.  After defeating the Russians at Tannenberg, the Germans attacked the Russian First Army at the Masurian Lakes.  This battle also ended in a Russian catastrophe, and set the tone for the entire war on the Eastern Front.  With some exceptions, the Russians always seemed to come up short in one critical part of the fight or another, and their continued incompetence and inability to win led, in large part, to the collapse of the Romanov dynasty and the Communist coup in 1917.

So, what are the lessons from these two battles?  From Mons, we should learn that no matter how excellent your army is, quantity has a quality all its own.  The Germans were well led and well equipped, and vastly outnumbered the BEF.  No matter how good the British soldiers and leaders were, they could not stand for long against the storm that was breaking across their front.

From Tannenberg, we can learn the opposite lesson.  With large numbers must also come expertise, at all levels.  The First and Second Armies were arguably the best formations that the Russians had, and they vastly outnumbered the Germans.  But incompetence on the part of their leadership, lack of discipline on the part of the soldiers, and failures to remember that the enemy rarely does as you think he will led to the destruction of both.  If you’re going to put together a large force, you have to make sure they are trained, equipped, and led well enough to win.

In other words, you can go too far either way.  A small, well-disciplined and led army can be overwhelmed, but a ponderous, massive army that is short on everything, especially leadership, can be easily cornered and dismembered.  Somewhere in the middle is the sweet spot of an army that is large enough to handle most opponents, but small enough that it can be led by mortals and equipped and trained without emptying the treasury.