The historian Graydon Tunstall called the Brusilov offensive the worst crisis of World War I for Austria-Hungary and the Triple Entente's greatest victory, but it came at a tremendous loss of life.

[26] The offensive's success led Russia's allies to reconsider their positions on postwar territorial concessions, including the status of Anatolia and the Bosphorus Strait.

The offensive is named after the commander in charge of the Southwestern Front of the Imperial Russian Army, General Aleksei Brusilov.

It inflicted irreparable losses on the Austro-Hungarian Army, and induced Romania to finally enter the war on the side of the Entente.

Under the terms of the Chantilly Agreement of December 1915, Russia, France, Britain and Italy committed to simultaneous attacks against the Central Powers in the summer of 1916.

This offensive took place at French request – General Joseph Joffre had hoped that the Imperial German Army would transfer more units to the east after the Battle of Verdun began in February 1916.

Franz Conrad von Hötzendorf had transferred Kövess' troops from the Balkans as well as four divisions from the Eastern Front.

According to Prit Buttar, "To make matters worse, many of the experienced divisions on the Eastern Front were withdrawn and sent to the Alps, and replaced by formations largely composed of new inexperienced recruits.

[31] General Alexei Evert, commander of the Russian Western Army Group based in Smolensk, favored a defensive strategy and opposed Brusilov's proposed offensive.

Although the Stavka had approved Brusilov's plan, his request for supporting offensives by the neighboring fronts (the Western under Evert and Northern under Aleksey Kuropatkin) was denied.

Alexander Winogradsky's artillery brigade used 76mm guns to open 24 breaches in the Austro-Hungarian defenses, coordinated in advance with the infantry commanders.

Winogradsky wrote, this was followed by a "creeping barrage in front of the assault infantry...while the 152mm howitzers and 122mm guns attacked hard points."

By the end of 7 June, the 4th Army retreat was unstoppable, with many elements of the X Corps surrendering when caught against the river, or casualties in attempts to cross.

[35] The initial attack was successful, and the Austro-Hungarian lines were broken, enabling three of Brusilov's four armies to advance on a wide front (see: Battle of Kostiuchnówka).

After four days into the offensive, Buttar states, "Brusilov's revolutionary tactics had been stunningly successful: artillery had been used with a precision that was unprecedented; infantry had worked their way close to the defences before launching their attacks; and those attacks had not used the traditional lines of men that were so easy for machineguns and defensive artillery to destroy."

[30]: 153–165 On 8 June, in response to appeals for help from Conrad, Erich von Falkenhayn organized five German divisions under the command of Linsingen, concentrating them near Kovel for a counterattack.

Pressure across a broad front forced the defenders to commit their reserves and left no sectors that could release troops to aid others."

[30]: 183–184 On 11 June, while pursuing the Austro-Hungarian Army in Bukovina, Russian forces inadvertently crossed into Romanian territory, where they overwhelmed the border guard at Mamornița and had a cavalry patrol disarmed and interned at Herța.

[30]: 211–231 From 27 June to 3 July 1916, Brusilov carried out, on his own initiative, the deportation of 13,000 German civilians from the Volhynian areas that had been conquered during the offensive.

[39] On 2 July, Evert's West Front finally started its offensive, with Alexander Ragoza's Fourth army attacking north of Baranovichi.

According to Buttar, "The fighting that extended from 28 July into early August was curiously disjointed...Although Lesh, Bezobrazov and Kaledin all launched their attacks on the same day, none of them were able to maintain their efforts for long..." Lechitsky's 9th Army and Shcherbachev's 7th Army made simultaneous attacks further south, with Lechitsky able to advance the front line to outside Stanislau, capturing it on 11 August.

The offensive was essentially over, according to Buttar, "Attacks continued on until the autumn rains turned the roads to mud, but other than add to the already terrible casualty list, nothing was achieved.

The early success of the offensive convinced Romania to enter the war on the side of the Entente, which led to the failure of the 1916 campaign.

According to John Keegan, "the Brusilov Offensive was, on the scale by which success was measured in the foot-by-foot fighting of the First World War, the greatest victory seen on any front since the trench lines had been dug on the Aisne two years before".

Brusilov used smaller, specialized units to attack weak points in the Austro-Hungarian trench lines and blow open holes for the rest of the army to advance into.

Similar tactics were proposed separately by French, Germans and British on the Western Front and employed at the Battle of Verdun earlier in the year.

In Russian society, pessimism regarding Russia's prospects in the war and distrust in the competence of its military and political leadership would continue to grow in 1916.