Fighting Soviet forces from the 4th Rifle Division and a combined cavalry brigade, its positions changed hands multiple times.

[9] On 5 July, the enemy broke through the Polish front both to the north and south of the bridgehead, with cavalry threatening to outflank the defending units.

In Hlybokaye, the remnants of the regiment were reinforced by soldiers from various First Polish Army units and formed into a battalion to defend the Olszanka line.

[11] At the end of August, the regiment returned to the front lines and participated in battles near Kutkorz and Milatyn, where it lost over 300 men, either killed or wounded.

The 3rd Battalion did not unload until the morning of 5 September, and after being bombed twice, it joined the regiment the next day and remained in reserve near the area of Koszyce.

[23] As part of the Kraków Army, the regiment was tasked with organizing the defense of the eastern bank of the Dunajec river, along a section from Zgłobice to Zbylitowska Góra, covering approximately 8 kilometers.

By the end of the 80 km march, the 3rd Battalion of the 39th Infantry Regiment had only half of its personnel remaining, as it had been engaged in fighting against German reconnaissance patrols.

[21] During the night of 8/9 September, due to an order for further movement towards the San river, the regiment began its march and reached the village of Węglówka by dawn.

[21] On 10 September, after 2:00 AM, during the continued march towards Barycz, the regiment was halted in front of the fortified defense of the 11th Infantry Division.

During the fighting near Jawornik Ruski and the subsequent march, Lieutenant Colonel Roman Szymański attended a meeting at the division headquarters.

[25] On the evening of 13 September, the commander of the Lesser Poland Army, General K. Sosnkowski, ordered the 24th Infantry Division to conduct a forced march toward Lviv to defend the Romanian bridgehead along the Dniester–Stryi line.

The 1st Battalion, led by Lieutenant Colonel Piotr Kaczała, surprised and forced the reconnaissance unit of the German 2nd Mountain Division to retreat.

[21] Upon reaching the Mościska region, the 39th Infantry Regiment, under divisional orders, continued its march through Tuligłowy to the Zarzecze Forest.

On the morning of 16 September, the regiment's vanguard reached Mużyłowice Kolonia, encountering fierce resistance from remnants of the III Battalion of SS-Standarte Germania, which had been routed the previous night by the 11th Infantry Division.

[21] Lieutenant Colonel Piotr Kaczała's 1st Battalion launched an assault, while the reconnaissance company of the 39th Infantry Regiment outflanked the German defenses.

[21] The 39th Infantry Regiment advanced to Mołoszkowice and then to the Yaniv forests (northwest of Lviv), where it took defensive positions in the "Na Chmurowem" woods along the southeastern and southern edges.

[21] After a brief stop in Yaniv, the composite battalion of the 39th Infantry Regiment marched toward Jamelnia, Kozice, and Rzęsna Ruska.

[21] With the road to Lviv cut off for General Sosnkowski's group, an order was issued to attack Rzęsna Ruska.

[21] The 39th Infantry Regiment's battalion fought its way into the northwestern part of Rzęsna Ruska, engaging in fierce combat for individual buildings.

[21] At 10:00 AM, upon Lieutenant Colonel Szymański's request, a composite battalion from the 1st Podhale Rifles Regiment under Major Serafiniuk was introduced.

Heavy casualties were sustained, including Major Józef Bieniek and Lieutenant Marian Żurawski, who were seriously wounded.

By midnight, General Sosnkowski reestablished contact with the commander of the 11th Carpathian Infantry Division and rescinded the previous order to disband the units and destroy heavy equipment.

[27] Around 8:00 PM, an attempt was made to break through to Lviv via a ravine leading from a military shooting range to Zboiska, but the German lines could not be breached.

[27] On the night of 20/21 September, a final group of 300–400 soldiers, including several dozen from the 39th Infantry Regiment, attempted to break through to Dublany and the Hungarian border under Lieutenant Colonel Szymański, Captain Domiter, and General Sosnkowski.

[1] On 29 April 1924, General Lucjan Żeligowski, on behalf of the President, presented the banner to the then-regimental commander, Colonel Edward Kańczucki.

[1] On 14 September, during the battle at Boratycze and Husaków, when German forces broke through the defenses, the banner's guard took it onto the battlefield, helping to restore order and suppress panic.

[30] On 23 April 1929, the Minister of Military Affairs, Marshal of Poland Józef Piłsudski, approved the design and regulations for the commemorative badge of the 39th Infantry Regiment.

[2] This color scheme was closely associated with the dark blue uniforms and yellow facings of the Polish infantry from the Napoleonic era and the November Uprising.

[31] The gorget, created by the 39th Lviv Rifle Regiment (descended from the Lwów Eaglets), featured an image of Our Lady of Ostra Brama and was presented with the inscription "To the Guardian of the City, as a lasting symbol of victory".

The design was created by Rudolf Mękicki [pl], and the piece was made of silver, partially gilded by Kazimierz Wojtych.