They were originally ordered by the Romanian Navy, but were confiscated by the French government while still under construction.

O'Byrne and her two sister ships (Henri Fournier and Louis Dupetit-Thouars) were ordered by the Romanian Government from the Schneider Shipyard in Chalon-sur-Saône, being laid down in April 1917.

The three submarines were subsequently completed for the French Navy, with larger bridges and conning towers.

Each vessel had a range of 1,850 nautical miles (3,430 km; 2,130 mi) at 10 knots (19 km/h; 12 mph) and a crew of 25.

[1] The O'Byrne-class submarines were originally ordered by the Romanian Navy, but were confiscated by the French government while still under construction.