Was attrition in WWI a rational strategy?

The short answer

• The bargain at Verdun. The attritional interpretation of Verdun depended on France losing men faster than Germany. That exchange was difficult to secure when German troops had to attack a fortress zone under its guns. Captured ground acquired a value of its own: by summer German prestige was tied to defending those gains, just as French prestige was tied to holding the city. The battle drew both armies into a costly defense of ground.
• Allies and the timetable. At Chantilly in December 1915 the Allies planned simultaneous offensives in the east, west and south. Pressure on several fronts would make it harder for Germany to move reserves where they were needed. Verdun interrupted the plan by absorbing French troops. The Somme, on ground selected where the British and French armies met, became a predominantly British operation launched partly to help France. Its timing and location reflected the demands of fighting as a coalition.
• Brusilov’s preparations. Brusilov spread his reserves across a wide front rather than massing them at one obvious point. Approach trenches reached within 75 meters of the Austrian lines, and aerial photographs helped prepare artillery fire. Surprise at many points struck an army already weakened by growing surrenders among some Slavic regiments. The advance outran its railways, German reinforcements strengthened the defense, and attacks near Kovel reverted to costly older methods. The preparations opened an opportunity that Russia's railways and neighboring commands could not sustain.
• Romania chooses its moment. Romania sought Transylvania, indicated by the blue arrow, and secured Entente promises before entering after Brusilov's victory made Austria-Hungary appear close to collapse. Its position was difficult: it bordered three enemies, its army lacked supplies, and Russian help came late and grudgingly. Defeat delivered a vital oilfield and an estimated million tons of grain to the Central Powers. The intervention intended to help end the war strengthened Romania's enemies. Bulgaria's timing in Chapter 6 and its eventual reckoning in Chapter 12 offer another view of a smaller power's risks.

What it changed

Losses and resources. The estimated losses are staggering: roughly 300,000 dead at Verdun, another 300,000 on the Somme, and perhaps a million Austro-Hungarian and Russian casualties in the east. Romania was overrun, while the western lines moved only kilometers. The resources left to continue the war also mattered. Germany ended 1916 outnumbered and blockaded, with the “turnip winter” beginning and a weakened ally to support. The Entente's greater resources would count over time, although its own armies had paid heavily for the pressure.

A weakened Habsburg ally. After Brusilov's offensive, Austria-Hungary depended increasingly on German divisions and command. Emperor Franz Joseph died in November 1916; within months his successor Karl secretly approached the French about peace. The empire that had helped start the war could no longer fight it alone. Its dependence forms part of the story of its rapid dissolution in 1918.

The survivors carry the war forward. Much of the French army had passed through Verdun. Many of those soldiers would face Nivelle's 1917 offensive and the mutinies that followed in part of the army. Veterans of the Somme carried costly experience into the BEF of 1918. The war also shaped later leaders: Charles de Gaulle was wounded and captured at Verdun, and Pétain commanded its defense. Their later decisions belonged to lives marked by the fighting of 1916.