September 2–4: Lithuanian attack The Lithuanians organized a counterattack to defend what they saw as their own lands on September 2 and the Marijampolė Group began its attack. The goal was to take and secure the Augustów–
Lipsk–
Grodno line. The centre column took Sejny on September 2. By the morning of September 4, the centre column reached the Augustów lake area through
Frącki and the Siersk forest, thus approached Augustów itself. The left column entered Lipsk on September 2,
Sztabin, the gorges of the Augustów lake and by the evening of September 3, also approached Augustów. Attacking on both sides of the
Kalvarija–Suwałki road on September 4, the right column reached the
Gulbieniszki–
Czerwonka–
Kaletnik line, fighting with the Polish near
Żubryn and Gulbieniszki, but failing to capture Suwałki. Also on September 4,
Kazys Škirpa's battalion from the centre column, which tried to take Suwałki from the east through
Krasnopol, was stopped at the
Wigry Lake and gorge. Nevertheless, the Lithuanians succeeded in reaching the outskirts of Augustów by September 4. The columns fought in isolation, lacked cavalry, and were forced to leave part of their forces for the protection of the rear, and did not enjoy the unanimous support of the population.
September 4–10: Polish counterattack On September 4, the Polish army, reinforced by units transferred from Suwałki, attacked the rear of the middle column, shot its commander K. Ramanauskas and the column disintegrated due to lack of command. The Poles counterattacked and forced the Lithuanians to retreat. On the Augustów-Lipsk section, the Polish army units, reinforced by a cavalry regiment and an infantry battalion, took over
Jastrzębna, so the left column, avoiding encirclement, withdrew from Augustów. On September 5, the Lithuanian army command ordered the Marijampolė Group to defend the line Lipsk–
Czarna Hańcza–
Wigry Lake–Kaletnik–
Fornetka––
Vištytis Lake. During the first week of the operation, the Lithuanian losses were the following: 21 soldiers and 2 officers killed, 37 soldiers and 2 officers wounded; 163 soldiers and 2 officers captured. Sections to be defended by the Lithuanian army were distributed by the command regardless of the area and available forces, without creating any reserves. The offensive of the Polish army was continued by
Adam Nieniewski's Operational Cavalry Group (2 provisional brigades, 8-9 cavalry and 1 infantry regiment). On September 7, it forced the Czarna Hańcza river. Then, on September 9, it seized Giby, Sejny, Kaletnik.
Lithuanian reorganization The
3rd Infantry Division led by Ignas Musteikis that was moved on September 9 to the Suwałki Region to stabilize the Lithuanian army's situation was deployed from the Vištytis Lake to
Żegary. The 3rd Division consisted of 2 regiments, 1 separate company, 2 batteries, squadron, with a total of 164 officers and 5,615 soldiers. Meanwhile, the 2nd Division was deployed from Żegary to Grodno. The Polish Front was formed and its temporary headquarters established on September 11, with
Maksimas Katche as commander.
September 13–22 Before the upcoming negotiations, the Lithuanian military leadership decided to improve its army's positions. The Lithuanians pushed back. Thus, the 2nd Infantry Division took over Sejny on September 13. On September 14, the 2nd Division entered Giby, approached the Mara River and the
Augustów Canal. Pending direct negotiations, hostilities were ceased on both sides that day. The negotiations in Kalvarija on 16–18 September 1920 ended without any agreement. Simultaneously, the Polish army had been planning a major offensive.
Polish offensive on September 22–23 On 8 September, during a planning meeting of the
Battle of the Niemen River, the Poles decided to maneuver through the Lithuanian-held territory to the rear of the Soviet Army, stationed in Grodno. Polish Northern Assault Group, consisting of infantry and cavalry divisions, was ready to enter action on 19 September, with the railroad hub of
Lida set as its objective. The most important (wing) group of the Polish 2nd Army consisted of the: •
1st Legions Infantry Division (4 regiments) •
1st Lithuanian–Belarusian Division (3 regiments) •
17th Infantry Division (4 regiments) • and
4th Cavalry Brigades (2 cavalry brigades) The Lithuanian forces had their two divisions assigned to two lines of defense, and outdated static and linear tactics were followed. On September 22, the Polish units began their attack. They pushed out the Lithuanian
5th and
8th Infantry Regiments from
Zelwa,
Budwiecie and
Berżniki, began to surround Sejny from the east, while others attacked from
Wiłkopedzie in the north. The
1st Legions Infantry Division of Colonel Dab-Biernacki attacked Lithuanian 2nd Infantry Division at Sejny, capturing the town after a six-hour battle. Following the capture of Sejny, the Poles marched towards Druskininkai and Lida. The
2nd Infantry Regiment, which fought west of the Sejny, was captured while retreating (headquarters with regimental commander Jonas Laurinaitis, 2 battalions, reconnaissance and communications teams, 6 artillery guns). Attacking the left wing of the 8th Infantry Regiment, the Polish army moved across the Mara River and occupied
Kapčiamiestis in the evening; thus scattering the regiment. The 4th Cavalry Brigade, after scattering Lithuanian infantry, captured bridges over the
Nemunas at
Druskininkai. On September 23, the Polish army reached the Druskininkai Bridge and moved across the Nemunas. Polish forces then marched, as planned on 8 September across the Nemunas near
Druskininkai and
Merkinė to the rear of the Soviet forces near
Grodno and
Lida.
Casualties During the battles of September 22–23, the Lithuanian Army's 2nd Infantry Division lost the following: • 32 soldiers and 2 officers killed, • 98 soldiers and 5 officers wounded, • 1,996 soldiers and 38 officers captured, • and 10 artillery guns. == Evaluation ==