The Brusilov offensive, also known as the "June advance", of June to September 1916 was the Russian Empire's greatest feat of arms during World War I, and among the most lethal offensives in world history. 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. It was arguably the most successful offensive in the entirety of the First World War. The victory contributed to a morale upsurge among the Russian troops, in 1917, Nicholas II planned a general general offensive along the entire front in order to end the Central Powers. After the victory, the Petrograd conference was held at which the post-war structure of the world was discussed.
Aleksei Alekseyevich Brusilov was a Russian and later Soviet general most noted for the development of new offensive tactics used in the 1916 Brusilov offensive, which was his greatest achievement.
In warfare, infiltration tactics involve small independent light infantry forces advancing into enemy rear areas, bypassing enemy frontline strongpoints, possibly isolating them for attack by follow-up troops with heavier weapons. Soldiers take the initiative to identify enemy weak points and choose their own routes, targets, moments and methods of attack; this requires a high degree of skill and training, and can be supplemented by special equipment and weaponry to give them more local combat options.
The Eastern Front or Eastern Theater of World War I was a theater of operations that encompassed at its greatest extent the entire frontier between Russia and Romania on one side and Austria-Hungary, Bulgaria, the Ottoman Empire, and Germany on the other. It ranged from the Baltic Sea in the north to the Black Sea in the south, involved most of Eastern Europe, and stretched deep into Central Europe. The term contrasts with the Western Front, which was being fought in Belgium and France.
The 1st Army was a field army-level command in the ground forces of Austria-Hungary during World War I. The army fought in Galicia and Russian Poland in 1914–15 before being briefly dissolved in the summer of 1916. Shortly afterwards, it was reformed and sent to fight in the Romanian Campaign for the next two years. The 1st Army was demobilized in April 1918 due to its heavy losses, following Romania's surrender.
Archduke Joseph Ferdinand of Austria, full name Joseph Ferdinand Salvator Maria Franz Leopold Anton Albert Johann Baptist Karl Ludwig Rupert Maria Auxilatrix; 24 May 1872 – 28 August 1942, was an Austro-Hungarian Archduke, military commander, from 1916 Generaloberst, and early advocate of air power. He later retired to live as a common citizen of Austria, and was briefly imprisoned in Dachau during the Nazi era.
The Gorlice–Tarnów offensive during World War I was initially conceived as a minor German offensive to relieve Russian pressure on the Austro-Hungarians to their south on the Eastern Front, but resulted in the Central Powers' chief offensive effort of 1915, causing the total collapse of the Russian lines and their retreat far into Russia. The continued series of actions lasted the majority of the campaigning season for 1915, starting in early May and only ending due to bad weather in October.
The Battle of Mărăști was one of the main battles to take place on Romanian soil in World War I. It was fought between 22 July and 1 August 1917, and was an offensive operation of the Romanian and Russian armies intended to encircle and destroy the German 9th Army. The operation was planned to occur in tandem with the Nămoloasa offensive; however, this operation was abandoned before it began.
The Battle of Limanowa-Łapanów took place from 1 December to 13 December 1914, between the Austro-Hungarian Army and the Russian Army near the town of Limanowa.
The Battle of Kowel took place during World War I, from 28 July to 8 August 1916. It began with an Austrian counter-attack by Alexander von Linsingen south of Kowel, a city located in the Volyn Oblast (province), in north-western Ukraine. Linsingen intended to halt the Russian offensive under the command of General Aleksei Alekseevich Brusilov.
The Battle of Kostiuchnówka was a World War I battle that took place July 4–6, 1916, near the village of Kostiuchnówka (Kostyukhnivka) and the Styr River in the Volhynia region of modern Ukraine, then part of the Russian Empire. It was a major clash between the Russian Army and the Polish Legions during the opening phase of the Brusilov Offensive.
The Rovno offensive — the operation of the Austro-Hungarian Northern armies against the armies of the Russian Southwestern Front — the so-called campaign on Rovno, or Lutsk-Rovno offensive operation. The purpose of the offensive was the liberation of Eastern Galicia, but by the end of the operation, a small part of Eastern Galicia was still held by the Russian Imperial Army.
The Battle of Komarow was a battle on the Eastern Front during World War I. It would prove a victory for the Austro-Hungarian forces, but one they would not be able to reproduce in the coming months of the war.
The Gorlice breakthrough occurred in the May 1–10, 1915 as part of the Gorlice–Tarnów Offensive during World War I. The German 11th Army led by General August von Mackensen, with the support on the flanks by the 3rd and 4th Austro-Hungarian Armies, defeated the 3rd Russian Army. For the first time in the history of the First World War a heavily fortified and long-term defensive position was broken through during the Gorliсе offensive.
The 12th Army was a field army-level command of the Austro-Hungarian Army that existed only for one month during World War I, led by Archduke Karl Franz Joseph. It had been formed in response to the success of the Russian Empire's Brusilov Offensive, and was dissolved upon the formation of Army Group Archduke Karl.
The 3rd Army was a field army-level command within the ground forces of Austria-Hungary during World War I. It was primarily active on the Eastern Front against the Russian Empire and in the Balkans against Serbia and Montenegro. Later on, the 3rd Army took part in some fighting on the Italian Front before returning to the eastern theater by 1917 to repulse the Kerensky Offensive. Its remaining units were merged with the 7th Army in January 1918.
Let the Thunder of Victory Rumble! is a novel by Boris Akunin, the second part of the third book on the adventures of Russian and German spies during the First World War. It describes the military adventures of Aleksei Romanov in the spring of 1916 in Galicia.
The 1917 Romanian Campaign consisted in three battles between late July and early September 1917, fought between Germany and Austria-Hungary on one side versus Romania and Russia on the other. Romania emerged from this campaign with a slight net territorial gain and won its most important battle during the First World War.
The Vistula–Bug offensive from July 13 to August 28, 1915, was a major Central Powers offensive with the decisive role of the German Imperial Army during World War I on the Eastern Front to defeat the forces of the Russian army in South Poland and Galicia.
The Second Brusilov offensive took place in July–August 1916 on the Eastern Front during the First World War. As a result of the First Brusilov offensive in May–June 1916, the Imperial Russian army defeated the Austro-Hungarian troops and captured a large number of prisoners. But Imperial German army came to the aid of its ally. In July 1916, all Austro-Hungarian troops were subordinated to Paul von Hindenburg and Erich Ludendorff and Hindenburg became commander-in-chief of the entire Eastern Front. The weakest sections of the Austro-Hungarian front were reinforced by German divisions, and most importantly, in the direction of the impending main attack of the Russian Southwestern Front, the defense was mainly occupied by German troops. The offensive in July–August, despite the use of enormous forces and resources by Brusilov, ended in failure. Three Russian armies attacked German positions east of Kovel, but to no avail. The colossal, unprecedented casualties for the Russian Imperial Army are indicated by the numbers of wounded on the Southwestern Front in July–August 1916 - the maximum numbers for the entire war on Eastern Front, exceeding the Russian casualties during the Great Retreat of 1915 under the attacks of the German Imperial Army:
July - 197,069 WIA
August - 172,377 WIA.
Austria-Hungary 
Russian Empire