Leszno and Rawicz were the strongest German centres (along with Bydgoszcz), which in January 1919 were outside the range of the territories captured by the insurgents. Poles were involved in offensive fighting on the Northern Front, where the German achievements were initially the greatest. However, taking offensive action along all sections at the same time was impossible. Thus, it was obvious that the Germans, who had two strong centres in the south-western part of Greater Poland, would try to take advantage of this to develop an offensive from this region, and the Poles would be left with nothing else to do other than to take defensive action.

In January 1919, the Germans made an attempt at the seizure of Osieczna using a force consisting of a unit of 60 people sent from Leszno. The objective of the plan was to attack the town from the south. At that time, a unit commanded by Sergeant Franciszek Muszyński was present in Osieczna. The Poles knew of the imminent threat, so they decided to take action to prevent a siege in the town itself and fight in the open. To this end Muszyński divided his unit into two groups. The first one was sent in a south-easterly direction along the road to Łoniewo, towards the Evangelical cemetery and the second one was to attack the approaching Germans from the area of Jeziorki.

Ultimately, the first group attacked the enemy, while the second one was drawing their attention with heavy fire from the front. At that time, 35 insurgents commanded by Sergeant Ignacy Talarczyk arrived from Kąkolewo after they had heard the sounds of combat. A counter-attack conducted with all the forces led to the retreat of the Germans. A certain amount of enemy armaments and equipment fell into the hands of the Poles.

The Germans did not give up and even on that same day, they started preparations for another expedition, this time conducted more precisely and with a greater number of soldiers involved. The Poles, being aware of these plans, also proceeded with preparations. In Jeziorki, in a brickyard located at a distance of about 5000m from the town and on the road to Łoniewo, about 400m from Osieczna, combat outposts were established. On 10 January, in the evening, the following units arrived:

– the Poznań company (about 150 people, commander: Second Lieutenant Jan Namysł),

– the Śmigiel company (about 130 people, commander: Second Lieutenant Józef Łukomski),

On 11 January, the Germans commenced other offensive activities. An armoured train was sent to Kąkolewo. It helped in driving out a unit consisting of 100 people from Kąkolewo. In this way, the attack on Osieczna from the south was safeguarded. Next, the Germans undertook activities against the town itself. The following units were sent to fight:

– the 1st company of the 37th Infantry Regiment,

– the 1st company of the 11th Grenadier Regiment (both companies consisting of about 250 in total),

– a half-battery of field cannons,

– mine launchers and heavy and light machine guns.

All of these forces were commanded by Lieutenant von Bismarck.

The Germans proceeded towards Wyciążkowo, west of Osieczna, and then in the early afternoon hours, they took up a line formation outside the town of Jeziorki. The insurgents, on the other hand, just like on the previous day, accepted a battle in an open field. The main forces took positions on the hills situated south west of Osieczna. The Śmigiel company took up a line formation north of the town, in parallel to the road connecting the Y-junction north of Jeziorki with Drzeczkowo. Despite heavy gunfire from the Germans and the fact that they used nerve gas, not only did the insurgents maintain their positions, but also forced the Germans to retreat in a daring counter-attack. The pursuit of the Germans continued until Gronówek.

The result of the skirmish near Osieczna, which was unexpected for the Germans, was a huge disappointment and even made them succumb to the atmosphere of panic in Leszno. The opportunity to seize the city was not taken however. The Poles owed their success to, on the one hand, the determination and the sacrifices made by insurgents, and on the other hand - the rather poor warfare skills of the German officer and the low morale of the units commanded by him. The respective Polish units fought almost independently, there was no joint commander for the defence of Osieczna. Conversely, it is hard to blame the insurgents for their failure to seize Leszno, when Kąkolewo was still occupied by the Germans, and about 250 people from Osieczna would not be able to hold the city in the case of an organised German counter-attack from Rawicz. As a result, it can be concluded that the skirmishes near Osieczna, just like the final result of all the fighting in north-eastern Greater Poland ended in success due to the unusual conditions of the developments in the economic, political and social situations in Germany in January 1919. Time eventually worked to the disadvantage of the insurgents - however, in that period, the conditions for the Poles were still favourable.