noun
military march
A piece of music composed for marching soldiers, often with a strong, regular beat.
運動会で軍隊行進曲が流れた。
A military march was played at the sports day.
行進曲 is a general 'march' (musical genre), while 軍隊行進曲 specifically refers to a military march.
Compound of 軍隊 (military) and 行進曲 (march). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning.