The Polish 1st Legions Infantry Division () is a tactical formation of the Polish Army. The division was formed on 20 February 1919 with veterans of the Polish Legions in World War I, whose traditions it carries. The division saw extensive combat during the PolishâÂÂSoviet War. Afterwards the division served with the Polish Army of the Second Polish Republic. In 1939, the division fought against Wehrmacht forces during the German Invasion of Poland.
As one of the most experienced and best equipped Polish divisions, it fought in many of the most notable battles of the PolishâÂÂSoviet War of 1919 and 1920. Among them was occupying Vilnius and Battle of Dyneburg in Daugavpils, Latvia (as part of Rydz-à Âmigà Ây's Third Army and under his personal command, although the actual commanding officer was Michaà  Karaszewicz-Tokarzewski). During the Kiev offensive of spring of 1920, the division formed the core of Operational Group and took part in the battle of Zhytomyr (April 25), capturing the city of Kiev itself (May 7). After the Polish withdrawal, the unit took part in heavy retreat battles and shielded the retreat of the rest of the Polish forces. After several clashes with the 1st Cavalry Army, the division broke off and reached the area of the Wieprz River, from where it started the counter-offensive during the Battle of Warsaw (see Battle of DÃÂblin and Mià Âsk Mazowiecki). On the second day of the Polish offensive, August 16, the division managed to outflank the Bolshevik Mozyr Group by a forced march of over 56 kilometres. After that the division, commanded by Stefan Dàb-Biernacki, was attached to the Second Army and took part in the second biggest battle of the war, the Battle of the Niemen River. During the battle, the unit formed the core of the Wilno Group and took part in a successful outflanking manoeuvre of the Bolshevik forces centered on the city of Grodno.
After that the division was moved to the rear and took part in shielding the border with Lithuania during à »eligowski's Mutiny. After the war, the division was partially demobilized and stationed in Vilnius as an en cadre divisional core. In the Second Polish Republic, the division consisted of three infantry regiments (1st, 5th, and 6th; all garrisoned in Vilnius), and other units, such as light and heavy artillery regiments, a company of cyclists, military engineers, and a mounted squadron.
Before the outbreak of World War II, the division, commanded by General Wincenty Kowalski, was partially mobilized in March 1939. As a part of the Wyszków Operational Group it was to shield the northern approaches of Warsaw from the German assault from East Prussia. After the outbreak of the Invasion of Poland, the division became fully mobilized and on 4 September 1939, it made contact with enemy troops in the forests around Dà Âugosiodà Âo. On 7 September it took part in heavy fighting near Puà Âtusk, but was outnumbered 3 to 1 and ordered to retreat southwards to defend the Bug River line between Kamieà Âczyk and Wyszków. Reinforced by 98th Heavy Artillery Detachment and 61st Light Artillery Detachment, the division successfully repelled a German assault near Braà Âszczyk, after which it began delaying actions while retreating towards Kaà Âuszyn. On 11 September that town was seized by German units and had to be retaken by force during heavy street fighting in the dark.
From there, General Wincenty Kowalski planned a counter-assault of his division. In what became known as the Battle of Kaà Âuszyn, on 13 September, the division started an all-out assault on German positions in nearby villages. After heavy fighting, the division broke through the third line of German defences in the villages of Lipiny, Debowiec, Wola Wodyà Âska, and Oleà Ânica. It finally broke through the German lines at Jagodno, but also suffered heavy casualties and lost most of its artillery and logistical support. Dispersed units crossed the German lines and joined several different Polish units, some of them formed ad hoc. The biggest group was rallied by the division commander but now numbered only three infantry companies out of an original three regiments. These troops broke through the forests near Radzyà  Podlaski to reach the units of Gen. Stefan Dàb-Biernacki and on 22 September took part in the successful Battle of Falków against parts of the German 8th Infantry Division. Shortly afterward the division effectively ceased to exist.
As a reaction to the Russian invasion of Ukraine of 2022, the Polish Ministry of National Defense decided to revive the unit. On 9 January 2023 Minister of National Defense Mariusz BÃ Âaszczak announced that the 1st Legions Infantry Division will be revived as an addition to the 16th Mechanized Division, stationed in Warmia-Masuria and 18th Mechanized Division, stationed in Masovia. The 1DPLeg will be the fifth mechanized division of the Polish Armed Forces.
The headquarters of the revived 1DPLeg are in Ciechanów
The 1st Legions Infantry Division is tasked to complement the defence of the BelarusâÂÂPoland border alongside the 16th Mechanised Division and the 18th Infantry Division. Polish Defence Minister Mariusz Bà Âaszczak stated that the formation is to "saturate" eastern Poland.
As an organised military formation, the 1st Legions Infantry Division is also tasked to support the Department for Civil Protection and Crisis Management in case of emergency.
The 1st Legions Infantry Division is to include a total of four brigades, which will consist of four maneuver battalions, one artillery battalion, one anti-aircraft battalion, one logistic battalion, and support companies. The division will be the largest Polish formation and equipped with Polish and South Korean equipment. As of 2025 the 1st Legions Infantry Division consists of the following units:
The 1st Legions Infantry Division does not deploy Soviet equipment. The Mechanized Brigades are equipped with K2 Black Panther and M1A2 Abrams SEP V3 main battle tanks; the artillery units are equipped with K9 Thunder and AHS Krab howitzers.
The co-presence of M1 Abrams and K2 Black Panther main battle tanks is a departure from the equipment of both the 16th Mechanized Division, which relies on Korean tanks, and the 18th Mechanized Division, which is equipped with M1 Abrams.
The formation will also have the Gladius unmanned aerial reconnaissance and strike systems.