Henning Hermann Robert Karl von Tresckow was born January 10, 1901 in Magdeburg (today in Sachsen-Anhalt), a descendant of Preussian nobility. Many of his forebears had been officers in the Preußian army and Henning also wanted to join the army badly. On August 13, 1917, he was posted to 1. Garde-regiment zu Fuß in Potsdam where he started his training. After graduation, he was sent to the western front in France in the spring of 1918 and was promoted to Leutnant in August. After the First World War had come to an end, Von Tresckow joined the 9. Preußische Infanterie-Regiment where he was considered a very ambitious man with a bright future ahead of him. Nevertheless, he decided to focus on a career outside the army which he left at the end of October 1920 to enroll as a law student at the Friedrich-Wilhelm University in Berlin. A year later, Von Tresckow continued his studies in Kiel but never graduated. In 1923 he started work at the Wilhelm Kann Bank in Berlin and with his intelligence and cold-bloodedness, he managed to make a lot of money on the stock market. He possessed a very convincing personality and combined this with gallantry and the readiness to discuss anything. This left a strong impression on many people. In 1924, Von Tresckow made a world wide tour through countries in Europe and North and South America which was quite a privilege in those days. Thereafter, Von Tresckow went into business.
In January 1926, Henning von Treschkow married Erika von Falkenhayn and one month later, recommended by Reichspräsident Paul von Hindenburg, he was drafted into the Reichswehr, established after the First World War, as Leutnant in the 9. Preußische Infanterie-Regiment. He wanted this badly because he felt home in the army and his banking activities offered him too little satisfaction in life. In the years that followed in Potsdam, where the regiment was stationed, the Von Tresckow couple had four children, Mark, Rüdiger, Uta and Heidi. Although Von Tresckow did not entirely reject national socialism in these years, that attitude gradually changed after June 30, 1934 when top members of the SA and a few other prominent men were executed by order of Hitler (Bio Hitler) during the Night of the Long Knives. This violence, instigated by the state and the SS in particular, made Von Tresckow realize that national socialism was an evil system but during the 30s he was not yet ready to resist. In 1934, Henning enrolled in the Kriegsakademie in Berlin-Moabit as Hauptmann; the study that gave access to the higher ranks. Von Tresckow excelled, he scored top marks on nearly all subjects making him a candidate for top functions.
After graduating from the Kriegsakademie he was posted to the department of Operations of the General Staff at the Reichswehrministerium in September 1936 where he learned a lot about the political events of the 30s. He was severely shocked by the so-called Von Blomberg-Von Fritsch affair in which these generals who voiced criticism and were highly admired by him were sidetracked by Hitler. In addition, Von Tresckow rejected the preparations for a war as he thought the army was not yet ready for it and because of his own conviction that each nation had already been assigned its own place in the European order. He was also severely shocked by the Kristallnacht in the night of October 9 to 10 because it was the state itself that was committing the crimes. Simultaneously, as a Preussian, he was bound to his duty and continued his work: cooperating in the preparations for war. If that was to happen nonetheless, it had to be done the right way. He also knew that if he would throw in the towel, someone else would take his place who would be a dedicated supporter of the Nazi party.