Watch A Soldier's Oath (1915) Official Trailer

While engaged in battle, Pierre Duval, a French soldier, stumbles onto the mortally wounded Count de Morave. Before dying, the count begs Pierre to deliver some family jewels and papers to the Vicomte Raoul de Reyntiens. At home, Pierre places the jewels in a box that also contains a necklace given to Margot, his wife, by the Duke D'Auberg. While stealing the box, Lazare, a war correspondent who witnessed Pierre's scene with the count, attacks and kills Margot. Found guilty of the crime, Pierre is sentenced to life imprisonment but is pardoned after performing a dangerous jailhouse rescue. Mavis, his daughter, who has been adopted by the duke, falls in love with the poor vicomte but is courted by Lazare, now posing as the Count de Morave. To win her love, Lazare gives her some of the stolen jewels, including the duke's necklace, but when Pierre sees the necklace later, he exposes Lazare and wins retribution.