On March 14, 1891, Major General Jozef Zajac, a pilot in the Polish Armed Forces, was born in Rzeszow. In August 1914, he joined the Polish Legions, initially serving in the 3rd Infantry Regiment as commander of a platoon, company, battalion and regiment. In July 1917, he commanded the 6th Infantry Regiment, and on August 1, 1917, he took command of the 5th Infantry Regiment. On March 15, 1918, he went with General Jozef Haller's Second Brigade to Ukraine, and 2 months later he was taken prisoner in the battle of Kaniów German, from which he escaped and made his way to France.
His service did not prevent him from pursuing an academic career, as he completed his doctoral studies in December 1915, receiving the degree of Doctor of Philosophy.
After arriving in Poland in May 1919, he headed the Regulations and Interpretations Committee of General Jozef Haller's Army Training Directorate, while also serving as commander of a group of infantry schools in Modlin and Rembertów. When the Polish-Bolshevik war broke out, he was sent to the front. On August 17, 1920 he became chief of staff, first of the 5th Army's "Lower Vistula" Operational Group, and then of the 2nd Army's Northern Operational Group.
On April 12, 1926 he was appointed commander of the 23rd Infantry Division in Katowice. On August 3, 1936, the President of Poland appointed him the Inspector of National Air Defense.
In 1937, he completed a pilotage course under the direction of Captain Henryk Wierszyłła. On May 4, 1939, he received the right to wear the badge of a military pilot of the third class. He flew the RWD-8 and was the Commander-in-Chief of the Air Force and Anti-Aircraft Defence during the September Campaign.
After the defeat, he made his way through Romania to France, where on October 6 he was put in charge of Aviation and Air Defense. On February 22, 1940, he became commander of the Polish Air Force.
On July 1, 1940, he was dismissed from his post to become deputy commander of the I Corps in Scotland in September. A year later he took command of the Polish Army in the Middle East. On May 3, 1942, he was promoted to the rank of Major General. He then became commander of the I Armoured and Motorised Corps in Scotland, and in 1946 served as Inspector of Army Training.
After his demobilization in 1948, he settled in Edinburgh, Scotland, where he began studying psychology and art history, receiving a doctor of philosophy degree in psychology in 1951.
He died in Ottawa after an illness of several days on December 12, 1963.