As a corporal in the 2nd Regiment of Mounted Riflemen from Hrubieszów, he took part in the 1939 Campaign, in which he distinguished himself by his bravery in the Battle of Mokra and participated in the daring night attack on Kamieńsk.

This was, at first, the so-called "OS" Special Branch in Polish[5] A partisan detachment was created and commanded by Basaj, as part of the BCh, during May of 1942, and initially conducted only small-scale actions against the Germans and their collaborators.

In the second half of 1942, there were four major clashes from which the "Ryś" BCh Partisan Detachment emerged victorious (at Kryłów, Mircze, Poturzyn and Kosmów ).

But Ryś was not content with such achievements, as on January 20, near Józefów, with only a hundred-strong unit under his command, he easily confronted the enemy forces, inflicting a defeat on them.

On 12 February the same year Stanislaw basaj successfully carried out an attack on Wereszyne during a wedding where 3 Ukrainian policemen were killed and some weapons were captured.

On March 18, the "Ryś" battalion carried out an operation against a detachment of Ukrainian nationalists in the village of Górki and, in pursuit of them, smashed a German car column, also destroying two cannons.

On 22 October, 4 platoons from the Basaj battalion smashed a detachment of the Ukrainian Insurgent Army and German gendarmerie, saving the pacified Polish village of Górka.

On 8 October 1943, Stanisław Basaj's "Ryś" BCh partisans, during their first joint combat action with Stefan Kwaśniewski's "Wiktor" Home Army unit, were to smash a Ukrainian police station in Mieniany.

[8][9] On 24 December of the same year two platoons of the BCh Stanisław Basaj "Ryś" unit came to the aid of the Polish population once again attacked by the UPA (Ukrainian Insurgent Army) militia in Kol.

A document of the Hrubieszów district BCh shows that also on 27 February the Ukrainian SD (ULS, 5th SS police regiment) arrived "in the liege".

On the same day still Basaj's battalion fought a victorious skirmish near Małkow with a unit of the SS Beyersdorf Combat Group, and with the Ukrainian National Self-Defence (USN).

Rescuing the Polish population, he attacked a detachment of the 14th SS Grenadier Division, as well as police and gendarmerie units pacifying the Górna and Łasków colonies, claiming another victory; on that day, Basaj and "Bold", going to collect ammunition, fought a battle with a Ukrainian militia in the village of Małków; 2 militiamen were killed and some weapons were captured.

[2][12] Throughout the month, Ukrainian partisan units and police officers carried out attacks on Poles, with several people falling victim to each (villages of Medycze, Terebiniec, Pielaki, Turka).

After pushing the Germans out of Małków, their forces were taken in ticks from 3 sides, the German expedition ended in defeat, many enemy soldiers and their commander were killed, the Poles captured a large amount of weapons and ammunition; the partisans lost 6 soldiers and 16 were wounded; the next day 3 platoons of "Rys" battalion and an AK platoon (commanded by "Huragan") under the personal command of "Ryś" smashed an outpost of Ukrainian nationalists in the village of Prehoryłe; several dozen Ukrainians were killed, the village was burnt down; during this action the UPA sotnia "Bradiagi" was smashed.

[15] In the summer of 1943, the Germans practically ceased their displacement actions in the Zamojszczyzna region, as they no longer had the strength to continue implementing the General Plan East, and pacifications and anti-partisan operations were carried out more with a view to ensuring security at the frontline; from the early spring of 1944, the Zamojszczyzna region experienced a new tragedy; the nationalist Ukrainian movement (OUN, UPA), aided by the Germans, undertook concentrated and ruthless actions aimed at pushing back or liquidating the Polish element from the south-eastern districts ofin Zamość (Hrubieszowski, Tomaszowski, Biłgorajski); at the end of February 1944, the Ukrainian Insurgent Army's command decided to move its operations to lands lying to the west of the Bug and San rivers.

A group of Ukrainian Insurgent Army under the command of Myroslav Onyszkewycz crossed the Bug River and massacred the Polish villages of Tarnoszyn, Posady and Podlody in the Tomaszów County, as well as the villages of Ostrów and Chlewiska near Bełżec, in the forest between Dachny and Monastyre Ukrainians murdered a Polish partisan group, including Soviet paratroopers and a unit of the Home Army "Krakusy"; at the same time, on the land Lubaczów In April they massacred Polish villages Budka and Chotylub, and the town of Cieszanów; in April and May new Ukrainian Insurgent Army units under the command of Col. Ostrózka, in the strength of a dozen or so thousand riflemen; they were aiming at taking over the regions of south-eastern Poland (within today's borders) and establishing a base of operations to fight the Poles; UPA's units were supported by German police, SS-Galizien units and other collaborator formationsIn connection with this, the UPA command categorically demanded that all Poles should leave parts of Chelm and Lublin regions by 6 April 1944, and in the first place the districts of Chelm, Zamojski, Hrubieszowski and Tomaszowski; in these areas, with the consent of the Germans, Ukrainian was introduced as the official language, in addition to German and Polish[16]

On March 8, 1944, concentrated units of Ukrainian police and the 14th SS Grenadier Division, supported by the USN units from Szychowice, Kryłów and Gołębia attacked the Prehoryłe colony; 4 platoons of the 1st BCh battalion "Ryś" and OP AK J. Ochman ("Kozak") rushed to help the pacified population; after heavy fights Ukrainian nationalists were driven out of the colony, leaving numerous corpses of murdered Polish inhabitants; the next dayUkrainians attacked the Prehoryłe colony again, murdering the inhabitants and burning the village, the "Ryś" battalion rushed to help the inhabitants.

Describing in his memoirs the preparations for, among other things, the attack on Szychowice and referring to the orders given to the commanders of the subordinate units and subdivisions assigned to carry it out, he bluntly stated:[17]"The objective was clear.

The Ukrainian data mentioning numerous civilians killed by Poles in Szychowice and Łasków was confirmed by the chronicle of the "Ryś" battalion.

When they surrounded one of the Basaj platoons in the village of Łasków, the main forces of the Basaj battalion and the "Wiktor" battalion moved to the aid of the surrounded population, "Ryś" drove the enemy out and captured the Mircze-Kryłów road, at the same time, the "Czarusia" and "Wiktor" companies of the AK drove the enemy away from the Sokal-Hrubieszów road and captured Mircze.

A bloody battle lasting many hours ensued, which ended in the defeat of the encircled units; 33 partisans were killed in the fight, and many were wounded.

The punitive expedition, commanded by Lt. Col. Werner Froemert, consisted of the Ukrainian Self-Defence Legion, sub-units of the 5th Galician SS Volunteer Regiment, a detachment of the German 154th Infantry Division, Ordnungspolizei officers and a battery of armoured guns.

[22][23] The Germans and their Ukrainian collaborators surrounded the "Ryś" battalion, as well as an AK outpost commanded by Mieczysław Olszak, alias "Hardy".

It was the last, unfortunately lost, big battle of the 1st BCh battalion of the Hrubieszów district; a few more smaller actions were performed and the fight was practically finished on 18 July 1944 with a skirmish with a detachment of Germans and Vlasov soldiers robbing the village of Stasin; the attackers withdrew, losing several dead.

On 25 March 1945 in the town of Kryłów Ukrainians organised an ambush into which "Ryś" fell, captured him and in a bestial way murdered him (crushing his body with a wheel), and then buried him in a place unknown to this day.

For harbouring an "enemy of Ukraine", the Uprising organised the so-called Bloody Sunday in Krylov, at which time 17 officers of the Civic Militia and 28 civilians were murdered.

He was interrogated in Liski Waręskie in the presence of the highest-ranking members of the Ukrainian underground in the Chełm region, including probably the OUN-B Security Service referent Łeonid Łapinśki 'Zenon'.

[30] The latest source research, witness testimonies and an accurate assessment of the political situation at the time after 22 July 1944 indicate that the murder was committed by an armed band of the Ukrainian Insurgent Army with the full approval or even assistance of the Hrubieszów UB or NKVD.

[30] Perhaps in the future it will be possible to clarify the whole truth about the tragic events of Sunday, 25 March 1945, to find out where "Rys" and the others were murdered and buried so that they can be given a dignified soldier's funeral.

Throughout the occupation, he led fight against the enemy, he created a large partisan unit, which in 1944 reached a strength of about 800 soldiers, and operated in the extremely difficult, usually forestless terrain where the Germans had begun the implementation of the General Plan East, with all its consequences, and soon later, German-backed Ukrainian nationalists attempted to create a 'Bander republic' and 'cleanse the Banderovska republic" and "purge" these lands of Poles.