Born on 2 July 1891 in Trześniów, Brzozów District, Lwów Voivodship at that time. After passing his matriculation exams at the Queen Sophia Middle School for Boys in Sanok, from 1910 to 1914 he studied at the Faculty of Law and Political Skills at the Franciscan University in Lwów.

From an early age, he was involved in independence-minded organisations. He was active in the "Zarzewie" organisation, and in December 1912 organised the Bartosz Group in Trześniów. It was then that he adopted the pseudonym "Ketling", which became a part of his surname. In August 1914, he was called up into the Austrian army; he took part in the battles of Kraśnik and Lublin, and commanded an infantry company during the winter campaign in the Carpathian Mountains and the Volhynia Region.

In July 1916, he was taken prisoner by the Russians, and after escaping in 1917, he joined the Polish Military Organisation. His way back to Poland led through Murmansk, England and France, where he joined General Józef Haller's "Blue Army". In April 1919, he returned to the country and fought on the Eastern Front in Volhynia and Galicia.

In April 1920, he was assigned to General Edward Rydz-Smigly's Front Command as chief of the Operations Department. In 1921, he completed his studies at the War College in Warsaw, after which he became chief of staff of the 2nd Mountain Division in Przemyśl. In 1929, he was assigned to serve as a successor to the commander of the 34th Infantry Regiment in Biała Podlaska, and in 1935, having already been promoted to the rank of colonel, he was appointed head of the Infantry Department of the Ministry of Military Affairs. In 1938, he was appointed divisional infantry commander of the 11th Carpathian Infantry Division in Stanisławów, and took command of it in August 1939.

In August 1939, he was ordered to set out westwards and on 4 September the division reached Bochnia, where it became part of the "Karpaty" Army. The division's task was to organise defence on the Wisłoka river line. On 14 September 1939, after heavy fighting near the village of Krzywcza, Prugar ordered its retreat towards Przemyśl. Prugar-Ketling was the author of one of the most spectacular successes in Poland's defensive war. Advancing towards Lwów, which was defending itself from the Germans, he defeated part of a strong motorised regiment of the SS "Germania" in the Battle of Jaworów on 15 and 16 September 1939. The fighting and lack of ammunition had exhausted the division's strength, so Prugar decided to disband it, after which it made its way to Romania, and then to France.

Due to the expansion of the Polish army in France, General Prugar was appointed commander of the 2nd Infantry Rifle Division in November 1939. During the French campaign of 1940, the division was diverted to the Belfort area, where it became part of the French 3rd Army. Under Prugar's command, the division resisted the German troops for four days, suffering heavy losses at Maiche, Trevillers and Dampprichart. With no way to break through to the west, about 12,000 soldiers of the 2nd Infantry Rifle Division crossed the Swiss border on 20 June 1940. That is where they were interned.

In a situation of inactivity and collapsed morale following the defeat of France, General Prugar-Ketling proved his organisational and commanding skills, which enabled the majority of soldiers, especially the young ones, to make the best use of their time in Switzerland. The general successfully organised student camps, middle school camps, and vocational courses for soldiers to become mechanics, radio operators, farmers and builders. 350 of them graduated from the universities of Winterthur, Gossau and Fribourg, 10 received a PhD and two – a habilitation. Soldiers of the 2nd Infantry Rifle Division were also required to work in a variety of sectors of the Swiss economy. They worked in the construction of roads, bridges and regulation of rivers and were employed in mines. Thanks to Prugar's initiative, the division carried out a wide range of cultural activities, publishing academic textbooks, school books, and scientific papers.

In September 1945, the general returned to Poland to discuss with the new authorities the conditions for the repatriation of his soldiers to Poland. He intended to create a "little Switzerland" in the country, a kind of settlement centre where soldiers who had lost their families and possessions in the turmoil of war could acclimatise to life in Poland. Most of the soldiers of the 2nd Infantry Rifle Division (around 9,000) returned to Poland, with around 800 soldiers remaining in Switzerland. The rest, with more than 2,500 soldiers, emigrated mainly to the USA, Canada and Australia. Prugar-Ketling himself returned to the country permanently on 17 December 1945. He began his service in the Polish People's Army (LWP). He was chairman of the Eastern Boundary Delimitation Commission and chairman of the Boundary Studies Commission, and was promoted to the rank of Major General in July 1947.

He passed away on 18 February 1948 in Warsaw. He was buried in the Avenue of the Distinguished at the Powązki Military Cemetery.

For his service, he was awarded the Gold Cross of the Virtuti Militari, Silver Cross of the Virtuti Militari, Commander's Cross and Officer's Cross of the Order of Polonia Restituta, Cross of Independence with Swords, Cross of Valour – twice, Commemorative Medal for the War 1918-1920, Gold Cross of Merit – twice, Medaille Interallee, French Order of the Legion of Honour 3rd and 4th class, French Croix de Guerre – twice, French Cross for Military Valour 1st class and the English Military Cross.