From 1938 to September 1939 he was Head of the course at the Higher Military School in Warsaw, after which he was appointed to the Division III of the General Staff as a Chief of the Department of Operations.
December 1939 – June 1940 Head of Division III, Polish General Staff in France.
He died in the plane crash on July 4, 1943, in Gibraltar, together with the Polish Prime-Minister and Commander-in-Chief General Władysław Sikorski and his staff.
On December 3, 2010, bodies of Tadeusz Klimecki, Andrzej Marecki and Józef Ponikiewski [pl] were exhumed, flown to Warsaw and then taken to the Department of Forensic Medicine in Cracow for examination.
On December 9, 2010, Tadeusz Klimecki and Andrzej Marecki were buried in the Powązki Military Cemetery in Warsaw.