The Battle of Radzymin () took place during the Polish–Soviet War (1919–21). The battle occurred near the town of Radzymin, some north-east of Warsaw, between August 13 and 16, 1920. Along with the Battle of Ossów and the Polish counteroffensive from the Wieprz River area, this engagement was a key part of what later became known as the Battle of Warsaw. It also proved to be one of the bloodiest and most intense battles of the Polish–Soviet War.

The first phase of the battle began on August 13 with a frontal assault by the Red Army on the Praga bridgehead. The Russian forces captured Radzymin on August 14 and breached the lines of the 1st Polish Army, which was defending Warsaw from the east. Radzymin changed hands several times in heavy combat. Foreign diplomats, with the exception of the British and Vatican ambassadors, hastily left Warsaw.

The plan for the battle was straightforward for both sides. The Russians wanted to break through the Polish defences to Warsaw, while the Polish aim was to defend the area long enough for a two-pronged counteroffensive from the south, led by General Józef Piłsudski, and north, led by General Władysław Sikorski, to outflank the attacking forces.

After three days of intense fighting, the corps-sized 1st Polish Army under General Franciszek Latinik managed to repel a direct assault by six Red Army rifle divisions at Radzymin and Ossów. The struggle for control of Radzymin forced General Józef Haller, commander of the Polish Northern Front, to start the 5th Army's counterattack earlier than planned. Radzymin was recaptured on August 15, and this victory proved to be one of the turning points of the battle of Warsaw. The strategic counteroffensive was successful, pushing Soviet forces away from Radzymin and Warsaw and eventually crippling four Soviet armies.

Background

Following the failure of the Kiev offensive, the Polish armies retreated westwards from Central Belarus and Ukraine. Although the Bolshevik forces failed to surround or destroy the bulk of the Polish Army, most Polish units were in dire need of fresh reinforcements. The Polish command hoped to halt the advancing Russian forces in front of Warsaw, the capital of Poland. At the same time General (later Marshal of Poland) Józef Piłsudski was to lead a flanking manoeuvre from the area of the Wieprz River, while General Władysław Sikorski's 5th Army was to leave the Modlin Fortress and head north-east, to cut off the Russian forces heading westwards, to the north of the bend of the Vistula and Bugonarew and on towards Pomerania. However, for this plan to succeed, it was vital that Polish forces hold Warsaw.

Prelude The defence of Warsaw was organized by the 1st Polish Army under General Franciszek Latinik and by a part of the Northern Front under General Józef Haller. The army consisted of four understrength infantry divisions: the 8th, 11th, and 15th, with the 1st Lithuanian-Belarusian Division in reserve. In addition, it had at its disposal the battle-weary 10th Infantry Division, two Air Groups (four escadrilles in total), 293 pieces of artillery and three armoured trains.

The city was to be surrounded by four lines of defence. The outermost ran some to the east of Warsaw: to the east of Zegrze Fortress, then along the river Rządza to Dybów and south through Helenów, Nowa Czarna and the Białe Błota marshes east of Wołomin. From there it ran through Leśniakowizna, dense forests occupied by artillery training grounds, and then along the Okuniew–Wiązowna–Vistula line.

The second line ran a mile closer to Warsaw, along the lines of partially preserved First World War-era trenches built by German and Russian armies in 1915, separated by a no man's land. It ran from the banks of the river Bugonarew at Fort Beniaminów, along the Struga–Zielonka–Rembertów-Zakręt–Falenica line. The two most prominent pivots of this line were the towns of Radzymin and Wołomin. The third line of defence ran in the immediate vicinity of the right-bank borough of Praga, while the Vistula River bridgeheads formed the final fourth line.

The 11th Polish Infantry Division was dispatched to Radzymin on August 8 in order to prepare the city's defences for the expected arrival of Bolshevik forces. While the unit's core was formed around veterans of the 2nd Polish Rifle Division of the French-equipped and trained Blue Army, it had been recently reinforced with fresh, but raw, recruits. The Poles set up defences in front of the town, utilising some earlier German and Russian First World War trenches and digging new positions. The Polish line ran some in front of the town, from the unfinished 1909 Fort Beniaminów at the banks of the river Bugonarew through Mokre to Dybów. The following day the 6th Russian Rifle Division captured Wyszków some to the north-east. On August 12 the Polish 1st Lithuanian–Belarusian Division abandoned the first line of defence and withdrew through Radzymin towards Warsaw. Radzymin now found itself at the front line; by nightfall, the first Russian forces appeared in front of Ruda and Zawady, two villages manned by the Polish 48th Infantry Regiment, and Russian artillery shelled Radzymin for the first time.

Battlefield From the north, Warsaw, which spans the Vistula, was effectively shielded by the Vistula, Bug and Narew rivers. The Red Army's lack of modern engineering equipment for the river crossings inhibited a flanking attack of Warsaw from the west, which had been Russia's historical path of attack, towards Płock, Włocławek and Toruń, where their forces could cross the Vistula and strike Warsaw from the west and north-west over permanent bridges there. While a ring of 19th- and early 20th-century Russian-built forts, part of the Warsaw Fortress, ran mostly along the western side of the Vistula, these fortifications lay in ruins; Russian forces began demolition in 1909 and had destroyed most by the time of their withdrawal from Warsaw in 1915, during the First World War.

The most expedient approach for a large-scale assault on Warsaw was from the east. The terrain was mostly flat; numerous roads converged radially along an arc from the Modlin Fortress to the north (where the Narew flows into the Vistula), to Legionowo, Radzymin, and Mińsk Mazowiecki directly to the east. Meanwhile, the only permanent defences in the area of Radzymin were the incomplete Fort Beniaminów and a line of First World War trenches west of Radzymin, neglected since their construction by Russians and Germans in 1915.

Opposing forces

The first and second lines of Polish defences were manned by regular forces. These included three Polish infantry divisions: the 11th (from the Bug River to Leśniakowizna), the 8th (Leśniakowizna to Okuniew) and the 15th (Okuniew to the Vistula River). The 1st Army also held the newly arrived 1st Lithuanian-Belarusian Division in reserve (Marki–Kobyłka), while the Northern Front's headquarters reserves consisted of the 10th Infantry Division and some smaller units. The third line was manned by units of mobilised State Police and a variety of volunteer units of low combat value. Out of those units, initially, only the 11th Division under Colonel Bolesław Jaźwiński took part in the fight. Its 48th Kresy Rifles Regiment (Colonel Łukowski) manned the Bugonarew-Mokre line, the 46th Kaniów Rifles Regiment (Colonel Krzywobłocki) manned the Mokre-Czarna perimeter, and the 47th Kresy Rifles Regiment (Lt. Colonel Szczepan) manned the Czarna–Leśniakowizna line. To the south of the 11th Division were positions around Wołomin manned by the 8th Infantry Division, consisting of the 36th, 21st and 33rd Infantry Regiments, as well as the 13th Infantry Regiment held in reserve, which later took part in the Battle of Ossów.

The combat value of Polish units is difficult to assess as they included fresh recruits of the so-called Volunteer Army, veterans of First World War, battle-hardened soldiers who fought in earlier stages of the Polish-Bolshevik War, and civilians with virtually no combat training. Prior to the battle, the 46th Regiment received 700 reinforcements: mostly deserters from various formations, a battalion of volunteer sentry guards and march companies of sappers. The 11th Infantry Division, nominally 9000 men strong, in practice had only 1500 soldiers in first-line units. The situation for the Polish Army was so dire that some of the soldiers sent as reinforcements had reportedly "never seen a rifle in their lives". In addition, most units to make a stand at Radzymin were exhausted after surviving a retreat from Belarus. However, the Polish side had superior intelligence and aerial superiority.

The two Russian divisions assaulting Radzymin were battle-hardened Siberian divisions led by experienced front-line commanders. Both divisions were as exhausted as their opponents, whom they had chased all the way from Belarus. However, prior to the battle both divisions received reinforcements from other units, instead of fresh recruits, and were much superior in manpower to other Russian units on the Polish front. Later, in his monograph on the war, Marshal of Poland Józef Piłsudski remarked that the commanding officer of the 27th Rifle Division had achieved what was unheard of in the Polish Army despite numerous attempts: putting rear echelons and stragglers of his division into front-line service. This was indeed a problem for both armies, as the number of "bayonets and sabres", or soldiers fighting in the first line, was at all times smaller than the number of second echelon troops. On August 15 Polish intelligence reported the strength of the Russian forces as "three to four standard Russian divisions".Jędrzejewicz & Cisek, p. 112 Even post-war memoirs by General Żeligowski mention "[t]hree Russian infantry divisions, that is 27 battalions, though admittedly understrength, against one of our own", though in fact the Russian forces only had two divisions.

Battle

August 13

Both Polish and Russian planners expected an attack on Warsaw—and Radzymin in particular—from the east. Yet the first fights started to the north-east of the Polish capital. Warsaw was to be assaulted from the east by the 16th Red Army. At the same time the 14th Red Army (under Ieronim Uborevich) captured Wyszków and started a fast march westwards, towards Toruń. It was then to cross the lower Vistula and assault Warsaw from the north-west. However, its 21st Rifle Division remained on the south side of the Bug River and headed for Warsaw directly, under orders from Russia's Commissar of War Leon Trotsky. Aided by the Russian 27th Rifle Division, it came into contact with the Polish forces at Radzymin on August 12, and prepared for an assault the following morning.

The Soviet probing attack began at 07:00 hours, but the 21st Rifle Division achieved no breakthrough. After the Soviets had been repelled, the defending 11th Infantry Division received some artillery reinforcements. The artillery commanders wanted to use the church tower of Radzymin as an observation post and to move the batteries forward, closer to the front line. However, before the relocation of the artillery was complete, a new Soviet attack began at around 17:00, this time carried out by four brigades of the 21st and 27th Rifle Divisions, reinforced with 59 artillery pieces. The Russians achieved a 3:1 superiority in firepower. Deprived of artillery support, the inexperienced and overstretched 1/46th Infantry Regiment, defending the village of Kraszew, broke, and the Soviets gained entry to Radzymin. The Polish unit withdrew in panic, and soldiers left their arms and backpacks behind. One of the artillery officers noted that the Russians achieved complete tactical surprise: "I ordered my dinner prepared when my aide came shouting 'Lieutenant Sir, the Reds are in the city.