Karl is a German who was living in France before the war started. He is married to Emile's daughter, Marie, and they have a son together, Victor. At the beginning of the game, Karl is deported to Germany shortly before the war begins, and is conscripted into the German army. He is 18 years old at the beginning of the war.
According to his official profile, Karl was born on May 6th, 1896, in a village near Strasbourg, Germany. His father was a Lutheran pastor, and the family atmosphere was cold and conservative. Though Karl received some education while growing up, he did not have the means or desire to attend secondary school.
In 1912, when Karl was 16, he left home and traveled around finding work at factories and farms in Belgium and France. He came to work at Emile's farm near St Mihiel in 1913, and decided to stay as a farm hand rather than moving on to another location like he had previously done. While working for Emile, Karl fell in love with Emile's daughter Marie, and married her. In 1914, they had a son, who they named Victor.
In the summer of 1914, Karl was deported to Germany. As of August 1st, Karl had arrived in Germany, and was conscripted into the German army.
Valiant Hearts: The Great War
Karl had been conscripted into the German army, and was made a pilot of Baron Von Dorf's battle zeppelin, however Von Dorf hardly ever listened to his warnings of engaging the enemy to close due to his caution of how resilient the French were, Von Dorf only did the risk in order to make himself more daring, and will allow himself to receive a promotion for bravery.
- Karl first becomes a playable character in Chapter 3, when he escapes the prisoner of war camp with Wilfried. He has non-playable appearances in Chapter 1, when Emile meets him at Neuve Chapelle, and again in Chapter 2, when Anna rescues him in Reims forest.
- The official character profiles state that Karl and Marie's son was born just before the war began; this was probably in June or July. Karl's first diary entry, where he describes being in Germany again, is dated as August 1st, indicating that he was deported in July. This means that Karl and Marie were only able to enjoy parenthood together for a month at most before Karl was forced to leave France. They were not reunited again until April 9th, 1917 - nearly three full years after they were separated.
- The date that Karl and Marie married is not stated in the game or character profiles, but must have taken place some time before September 1913.