There are few interesting facts about that special holiday. To start with, you can read almost everywhere that February 23 was chosen in honour of the first victory of the Red Army over the Kaiser's German troops near Narva and Pskov in 1918. Thus, from 1923, по приказу Реввоенсовета Республики (by orders of the Revolutionary Military Council) the holiday was known as День Красной Армии (The Red Army Day).
Actually, the Red Army never stopped the German offensive on that day, but two years later, in 1920. The idea of this fraud comes from Stalin himself, in 1938, because he couldn't accept the notion of a celebration not being related to a special event. It took nearly 60 years for the fraud to be recognised and corrected by the State Duma. Indeed, in 2006's decree, the description of the holiday omitted the “Day of victory of Red Army over the German Kaizer’s troops (1918)”
Since 1949, this holiday became known as День Советской Армий и Военно-Морского Флота (Soviet Army and Navy Day).
After 1991 and the collapse of Soviet Union, the name of the holiday was changed again and became День защитника Отечества (Defender of the Motherland Day). Officially, it celebrates men and women who were serving or are serving the Russian Armed Forces. But somehow, nowadays it is better known as “День Мужчин” (Men’s Day). It became a custom to congratulate men and offer them little presents. A way to compensate Восьмое марта (International Women’s Day).
The Defenders of the Motherland Day is not only celebrated in Russia, but in several other former republics of Soviet Union, under different names.