The arming of the Russian squadron assigned to operations in the Mediterranean served as a pretext for war.
21 June — a detachment of Swedish troops crossed the border, broke into the outskirts of Nyslott, and began bombarding the fortress. The Russians managed to assemble only about 14,000 troops (partly newly recruited) on the Swedish border; facing them was a 36,000-strong enemy army under the personal command of the king. Despite such an inequality of forces, the Swedes achieved no decisive success anywhere. Their detachment besieging Nyslott was forced to retreat, and in early August the king himself, with all his troops, withdrew from Russian territory.
6 July — near Gogland there was a clash between the Russian fleet and the Swedish fleet commanded by the Duke of Sodermanland. He was forced to take refuge in the Sveaborg harbor, losing one ship in the process. Admiral Greig sent his cruisers westward, thereby cutting off all communication between the Swedish fleet and Karlskrona.
17 December — Russian troops under Prince Potemkin captured the Turkish fortress of Ochakov on the Black Sea coast near the mouth of the Dnieper. The battle was brutal: the entire Turkish garrison was destroyed. The capture of this strategic fortress allowed Russia to firmly secure its position in the Northern Black Sea region.
The 1788 campaign was conducted by the allies sluggishly and unsuccessfully. Potemkin's army crossed the Bug only in June and laid siege to Ochakov in July. The Turkish fortress was of strategic importance as one of Turkey's main strongpoints in the Northern Black Sea region. One of the bases of the Turkish fleet was located here. Ochakov made it possible to control the exit from the Dnieper-Bug Liman (into which the Dnieper and Southern Bug rivers flow) into the Black Sea. With the help of French specialists, the Turks managed by the beginning of the 1788 campaign to prepare the fortress for defense: to reinforce the garrison, restore old fortifications, and prepare new ones. The Ochakov fortress adjoined the Liman on one side (the least protected). The walls were covered by an earthen rampart and a ditch. On the approaches to the fortress itself there was a first line of defense—earthen fortifications. About 300 guns were installed on the ramparts and walls, and 30 cannons on the fieldworks. Separately from the fortress, on the top of Cape Ochakov, stood Hassan Pasha's castle. The fortress was supplied with food and ammunition calculated for a long siege. In addition, the fortress garrison counted on support from the Turkish fleet. As a result, the siege dragged on until December 1788. Ochakov was blockaded on land by the army, and from the side of the Liman by a flotilla, which successfully repelled all attempts by the Turkish fleet.
It is worth noting that the young Black Sea Fleet acted very actively and decisively against the enemy fleet, which was trying to help its fortress and the Turkish Dnieper flotilla. In the battles of 7 June and 17 June, the Russian Dnieper flotilla under Admirals John Paul Jones and Karl Nassau-Siegen, and Captain Panagioti Alexiano, repelled attacks by the Turkish fleet. On the night of 18 June, the Turkish fleet decided to leave Ochakov and, during the withdrawal, came under fire from coastal batteries installed by Suvorov. The rout was completed by the Russian ships that arrived in time (Rout of the Turkish fleet in the Battle of Ochakov). In the two-day Battle of Ochakov, the Turks suffered heavy losses: 15 ships, including 5 ships of the line and 5 frigates, carrying about 500 guns. The Turkish sailing fleet was forced to withdraw to Varna. On 1 July, the Russian flotilla finished off the Turkish Dnieper flotilla near Ochakov. And on 3 July, the Russian sailing squadron under Voinovich and Ushakov defeated the Ottoman fleet near Fidonisi (Battle of Fidonisi). At the end of July, the Turkish fleet again approached Ochakov, but after it departed at the end of October, the fortress was doomed. Thus, the Russian fleet did not allow the Turks to provide full support to Ochakov from the sea. The unconditional dominance of the Turkish fleet in the Black Sea was coming to an end.
The main forces of the Russian army were tied down by the siege of Ochakov. The commander-in-chief acted extremely sluggishly: for five months a large army stood under the fortress walls, facing a 15,000-strong Turkish garrison led by Hassan Pasha. The brave Suvorov, commanding part of the army, repeatedly proposed a decisive assault with the support of the Liman (Dnieper) flotilla, but Potemkin hesitated. The commander-in-chief decided to conduct a formal siege, fearing failure. The troops began building redoubts with artillery batteries to protect the flanks; then they planned to take the suburb, move the guns forward, connect them with a trench, and begin a methodical bombardment of the fortress, forcing the enemy to surrender. Mining under the walls was impossible due to the hardness of the ground.
During the siege, the Russian troops repelled a series of sorties by the enemy garrison, which tried to interfere with the engineering works. A particularly large attack was repelled on 27 July. Suvorov personally led two battalions of grenadiers in a counterattack and repulsed the enemy assault, being wounded in the process. He proposed immediately storming the fortress and taking it before the enemy recovered. However, Potemkin again refused to assault. The wounded Suvorov handed command of the troops to General Bibikov. During the siege of Ochakov, other Russian heroes also distinguished themselves—Bagration, Kutuzov, Barclay de Tolly, Platov. Thus, on 18 August the Ottomans again made a sortie from the Liman side against the left flank of the Russian army. During a four-hour battle, the attack was repelled; Turkish losses in killed and wounded were about 500 men, while Russian losses amounted to 152. In this battle, Major General Kutuzov, chief of the Bug Jager Corps, distinguished himself and received a second head wound. A bullet entered his cheek and exited through the back of his head; he again survived by a miracle.
The siege was extremely hard. A damp, cold autumn gave way to an early and ferocious winter (long remembered by the people as the Ochakov winter). The army was poorly prepared for a siege. The soldiers suffered from shortages of uniforms, provisions, and fuel. In the bare steppe there was no forest for heating. There was no fodder; almost all the cavalry dismounted. Soldiers froze in their dugouts and themselves asked for an assault in order to end the hated siege sooner. In such conditions, the troops lost more men than in battle. Empress Catherine II, who was waiting for news of victory, was displeased with her powerful favorite. The influence of his opponents grew. In St. Petersburg a biting remark by Rumyantsev circulated: "Ochakov is not Troy, to besiege it for ten years." In November, the sovereign sent a rescript to the prince to finally take up the matter energetically.
Meanwhile, the enemy's defense weakened. Russian troops moved closer to the fortress and built two lines of field fortifications, where 30 artillery batteries with 317 guns were placed. The bombardment of Ochakov was conducted both from land and from the ships of the flotilla. By early November, the Ottomans had lost most of the guns in the forward fortifications. The bastion of the fortress adjacent to the Liman was badly damaged. Most buildings in the city were destroyed or burned. In November, a flotilla of Cossack boats under Ataman Golovaty, covered by ships of the Dnieper flotilla, carried out a swift raid on the fortified island of Berezan, located in front of Ochakov. The Ottomans capitulated; 320 men laid down their arms. The Turks handed the Cossacks the keys to the fortress, more than 20 guns, 11 banners, 150 kegs of gunpowder, and other supplies.
Only after the plan of a formal siege failed and the enemy still stubbornly refused to capitulate did Potemkin decide to attack. It was necessary either to lift the siege and return in disgrace, or to undertake a desperate assault. The start of the attack was postponed several times due to bad weather conditions. In early December, the commander-in-chief approved the operation plan prepared by General-in-Chief Meller. To ensure the strike's surprise, they abandoned preliminary shelling of the fortress.
6 December — at 7 a.m., in 20-degree frost, 18,000 soldiers launched a decisive assault on Ochakov (the siege corps itself then had about 21,000 men remaining). Six assault columns went into battle, simultaneously attacking the earthen fortifications surrounding the Ochakov fortress, Hassan Pasha's castle, and the fortress itself. At first, the earthen fortifications between the Ochakov fortress and Hassan Pasha's castle were taken. Then the Russian soldiers attacked the Turkish fortifications in the center and reached the walls and gates of the fortress itself. Under cover of artillery fire, the grenadiers broke onto the walls and opened the gates for the troops that had taken the forward fortifications. The Turks, driven off the city walls, took shelter in houses, fought in the streets, and offered desperate resistance. Hand-to-hand combat inside the fortress lasted about an hour. Most of the fighters in this clash died from edged weapons. Hardly any prisoners were taken inside the fortress.
The battle was bloody and marked by extreme ferocity. Two thirds of the Turkish garrison were killed; 4,500 were taken prisoner, including the commandant Hassan Pasha (Hussein Pasha) and about 450 officers. The fortress was littered with bodies. There were so many corpses that, unable to bury them in the frozen ground, thousands of bodies were taken out onto the ice of the liman, where they lay until spring. Among the trophies were 180 banners and 310 guns, as well as much weaponry, equipment, and various supplies.
Our losses were 2,289 killed and wounded. It is clear that after the prolonged siege of Ochakov there could be no talk of capturing Bender. Potemkin withdrew the army to winter quarters and left for the capital himself. For the capture of Ochakov, His Serene Highness the prince was awarded the Order of St. George, 1st Class, and received other generous rewards. The siege corps was paid an additional half-year's salary. In 1789, a medal "For Bravery Shown at the Capture of Ochakov" was instituted. The medal was awarded to NCOs and enlisted men of the army who took part in the siege and assault of the Ottoman fortress. A total of 15,384 silver medals were struck.