Hitler's uniquely shaped mustache has made his figure even more iconic.

The box-shaped mustache attached to him has its history behind it.

As reported by The Daily Star, based on a series produced by the History Channel, Hitler had to shape his mustache to wear a gas mask properly during his involvement in World War I. This is because when he still had a long mustache with long ends, he could not wear it. This is because when he still had a long mustache with a twisted end, his gas mask could not be tightly closed when dealing with a gas attack.

Gas masks or respirators were an essential part of the German armor at the time due to the threat of gas attacks from the British in 1918, which were sprayed continuously.

However, Stephen David, executive producer of the series, said that his research team learned that Hitler preferred a long mustache before World War I broke out.

The toothbrush mustache was introduced in Germany in the late 19th century after visiting America.

According to another source, Adolf Hitler's sister-in-law, Bridget Hitler, is known to have fought with him because she couldn't stand the mustache and persuaded him to cut it off.

In 1923, his future publicist Ernst Hanfstaengl, who later adopted the style, advised him to remove his toothbrush mustache. But Hitler replied, "If this is not fashionable now, it will be fashionable later because I wear it."

Hitler's mentor, Anton Drexler, wears a notched version of the toothbrush mustache.

Then Friedrich Kellner, a Social Democrat who campaigned against Hitler, also wore the style.

In addition, many Nazi figures other than Hitler had similar mustaches, including Heinrich Himmler, Karl Holz, Ernst Röhm, and Hitler's driver, Julius Schreck.

Comedian Charlie Chaplin was even known to have the same mustache style.