- This article is about an in-universe event. For the in-game mission, see Diapason.
- "Ring the freedom bell louder! Make it known throughout the city!"
- ― Civilian
Operation: Constantine, also known as the Battle of Directus or Liberation of Directus, was the military operation performed by the Allied Forces to liberate Ustio's capital from Belkan rule. This battle made the Galm Team, more specifically its leader Cipher, very popular among the Ustians.
Thanks to the success of Operation Varsity at Solis Ortus the day before, the Allied Forces had the opportunity to spearhead into Directus. Taking back control of the capital from the Belkan Army would guarantee Ustio the ability to take back control of its entire country.
On May 13, the Allied Forces sent the Galm Team and an Osean Army division from the south to Directus. Simultaneously, Ustio's army invaded Directus from the north. This pincer maneuver would ensure the Belkan Army could not escape.
As the Osean army engaged from the North and the Ustian army from the South, the civilians began to resist the Belkan occupation forces. They used anything they could find to fight or stall the Belkans with. In a symbolic act now repeated every night in Directus, the Ustians broke into a church to ring the "Freedom Bell" which rang across the city, signifying that liberation had come.
Thanks to the overwhelming air power of the Galm Team, the Belkan forces quickly lost air superiority, turning the ground forces into sitting ducks. As Galm continued to liberate each and every one of the five sectors, the Belkan Army Major General, commander of the present Belkan army, attempted to flee the city by helicopter. He was quickly shot down by Cipher.
Within a few hours, the Belkans had lost control of all five sectors of Directus. The Belkan Army had been defeated. Belka had sent the 23rd Tactical Fighter Squadron "Gelb" as back-up, but they had arrived at the combat zone far too late to do anything. They still engaged the Galm Team, but they were shot down. With the loss of reinforcements, the Belkan Army surrendered to the Allied Forces.
Immediately after the battle's end, the civilians were shouting for freedom, praising Cipher as he flew above the Directus airspace. This was a huge morale boost for the armies and pilots of the Allied Forces, especially those from Ustio who recognized the Freedom Bell's sound.
This battle also signified a dramatic shift in the war; Belka was now on the defensive. They fell back to the first line of defense, the Hydrian Line, and as the Allies prepared to invade Belka, the darkest days of the war were about to begin.
- The way the citizens in Directus revolted against the Belkans to help the Allies retake the capital is similar to how, in real life, the French Resistance assisted the Allies in World War II by revolting and assisting in taking Paris from the Nazis.
- Which citizen speaks at the end of the mission and his/her speech context depends on the player's ace style (a floral designer on Mercenary, a baker on Soldier, and a clockmaker on Knight).