Why is control of Constantinople important for Russia?
This is because I have to go through two reasons:
Constantinople was the center of the Orthodox Church
Controlling Constantinople meant guaranteeing access to the Mediterranean Sea and not posing a threat to its southern border
The Hagia Sophia is depicted as a church
1. Constantinople is the center of the Orthodox Church
Since the Great Schism of 1054, Orthodox Church has been concentrated in Constantinople, which was then the capital of the Roman Empire. For most of the Middle Ages, important institutions such as the Christian Patriarchate of Constantinople were the main voices of Eastern Christendom. In addition, it was a very prestigious city, with scholars and other scholars coming here from other Orthodox Christian cities such as Antiochus and Alexandria. In short, if you are an avid Orthodox Christian, Constantinople is the ideal place to live, home to some of the most iconic sights, such as the Hagia Sophia.
By the 1400s, the once-mighty Roman Empire had declined into an unrecognizable entity. It was broken, and the once grand Constantinople was sacked and lost many of its inhabitants. This proved to be ideal for progressive Muslim Turks, who slowly but surely occupied more and more land in the Balkans and Anatolia. Eventually, the city was conquered by the Ottoman Empire in 1453, and the Orthodox Church was humiliated when the conqueror Muhammad converted the Hagia Sophia into a mosque.
At the same time, in northeastern Europe, an Orthodox state called the Grand Duchy of Moscow or The Duchy of Moscow was becoming increasingly powerful. Their grandstand on the Ugra River ended the tatar yoke and ensured complete independence. However, with the fall of Constantinople, Moscow gained more responsibility as the seat of the "Third Rome", the Orthodox Church. After all, they are the most powerful Orthodox states, and many Orthodox adherents are under the rule of other churches or religions. With this new role, Moscow, and then Russia in 1547, would continue to spread its faith in the steppes and then try to expand along the Black Sea.
Meanwhile, the Ottoman Turks seemed invincible and ambitiously expanding in Europe, but everything changed in 1683 at the gates of Vienna, where the Ottoman Empire suffered a devastating defeat. Thereafter, the Ottoman Empire gradually declined, allowing Russia to pursue its goal of seizing Constantinople as an Orthodox seat. There will be many attempts to do so, but in the end they all fail. Nevertheless, they did manage to do their part in liberating many Of the Orthodox states of the Balkans, such as Bulgaria and Serbia, which to some extent legitimized their claims as Orthodox Christian leaders.
2. Control of Constantinople means that access to the Mediterranean sea is guaranteed and that there is no threat to the southern border
Although controlling Constantinople meant consolidating their position as the "Third Rome", it also had very important strategic and economic value. As a city with a population of 400,000 (estimated at 1,800 people), this will be a good economic boost for the Russian economy. In addition, Constantinople has been a major trading center for centuries, attracting many merchants and merchants, who will also play their part in increasing Russia's monetary strength.
Of course, controlling the Bosphorus would also guarantee access to the Mediterranean, thus easing trade with other European countries. Given the less than ideal relationship between the two, giving the Ottoman Empire control of Constantinople was always risky. One of the main reasons Russia moved its capital to St. Petersburg was to improve trade between them and other European countries. Apparently, due to the possibility of the Ottoman blockade, it was impossible to transfer it to their Black Sea cities.
Strategically, Russian control of Constantinople will allow Moscow to exert greater influence over North Africa and southern Europe. Their navy's efforts in the Mediterranean will be unhindered and will eliminate any threat to Russia's southern borders, as was the problem Russia encountered in the Crimean War. Britain and France repeatedly went to war with Russia to keep the fragile Turkish Empire alive, in an effort to prevent Russia from gaining full dominance in Eastern Europe.
Map of Europe in 1871. By this time Russia had intensified its attempts to annex Constantinople.
Constantinople was one of the main targets of the Russian Tsar until its final end. In World War I, together with France and Britain, they planned to separate the corpses of the Ottoman Empire. Once the Turks were taken care of, the Constantinople Agreement secured the holy city for the Russians. Unfortunately for them, the Russian Revolution and the subsequent Bolshevik government halted Russia's demands on the city once and for all, shifting the focus to spreading The Chauvinism of Russia's great power rather than orthodox Christian hegemony.