The 25th Reserve Division began World War I on the Western Front, fighting through Belgium and France in what became known as the Allied Great Retreat, culminating in the First Battle of the Marne. It then participated in the Race to the Sea, fighting in Flanders and the Artois, including at Lille. In December 1914, it was sent to the Eastern Front. In 1915, it participated in the Gorlice-Tarnów Offensive, including the battles at Lemberg (now Lviv) and Brest-Litovsk. It then fought in the Serbian campaign. After this campaign, the division was transferred from Macedonia back to the Western Front. After several months' fighting in the Argonne Forest, the division entered the Battle of Verdun in July 1916, where it suffered heavy losses. It also faced the French offensive in August 1917 at Verdun, where it again suffered heavy losses. In 1918, the division faced Allied offensives at the Battle of Cantigny, Montdidier and Noyon, and in the Somme Offensive, again taking heavy losses. The division was dissolved on 20 October 1918. Until 1918, Allied intelligence rated the division as second class, but downgraded it based on its use by the German high command and performance in battle.