The four ships were however requisitioned by Italy in 1915 and rearmed as scout cruisers (esploratori), subsequently seeing service in World War I.

The four warships were ordered in 1913 by Romania, from the Pattison Shipyard in Naples, with the names Vifor, Viscol, Vârtej and Vijelie.

[1] Aquila, Nibbio, and Sparviero entered service in the Italian Regia Marina (Royal Navy) in time to take part in the later stages of the Adriatic campaign of World War I.

Aquila took part in the largest surface naval engagement of the war in the Adriatic Sea, the Battle of the Strait of Otranto, on 15 May 1917, during which the Austro-Hungarian Navy destroyer Csepel scored a hit on Aquila′s boilers which immobilized her, and she had to be towed back to port.

[4][6] Falco was completed in 1920, too late for World War I, but she and Aquila served in the Regia Marina during the interwar period.

[16][17] Despite having their heavy armament reduced to destroyer standards, the two warships still presented some cruiser characteristics, such as retaining their torpedo tubes mounted on the broadsides instead of the centerline.

During World War II, Mărăști and Mărășești were the most heavily-armed Axis warships in the Black Sea, and had the greatest standard displacement.

Both ships were active during the Romanian naval campaign in the Black Sea in World War II, mainly providing escort for Axis supply convoys between Romania, the Crimean Peninsula, and the Bosphorus.

On 26 June 1941, Mărăști helped repel a Soviet naval attack against the main Romanian port of Constanța, together with the destroyer Regina Maria and the minelayer Amiral Murgescu.

[18][19] During Romania's participation in the war on the side of the Axis, Mărăști carried out a total of 28 escort missions and Mărășești 21.

To conceal the fact that Italy was selling ships to Francisco Franco's side in the war, the two warships were often referred to as Velasco-Ceuta and Velasco-Melilla, and the Spanish Nationalists added a dummy fourth funnel to each ship to increase their resemblance to Velasco, the only non-ex-Italian destroyer under Nationalist control.

[9][10] Melilla and Ceuta saw heavy service — primarily in surveillance and escort tasks — during the Spanish Civil War in spite of their poor condition.