This four characters '大井寺奴' (Oi-dera no Yatsuko [servants of Oi-dera Temple]) recorded in "Nihonshoki" proves that the common people were widely mobilized as soldiers, and this is also an example that Yatsuko (or Yakko, male slave) of ancient Japan fought bravely as soldiers.
「大井寺奴」の4字は、兵士が民衆的な層から広く動員されたことを教える証拠であり、また、古代日本の奴（奴婢の男）が兵士として勇戦した例でもある。