Ivan, having now secured both banks of the Volga, prepares for a campaign to force an exit to the sea, a traditional concern of landlocked Russia.

He feels that trade with Europe depends on free access to the Baltic and decides to turn his attention westward.

By invading the territory of the weakened Livonian Knights (present Estonia and almost all of Latvia) in 1558 in an effort to prevent Poland-Lithuania from gaining dominance over it, he initiates the so-called Livonian War.

The Livonian Confederation has by the late 1550s disintegrated over a series of internal disputes, while its Eastern neighbor Russia has grown stronger after annexing the khanates of Kazan and Astrakhan in 1552 and 1556, respectively.

The conflict between Russia and the Western powers is exacerbated by Russia's isolation from sea trade.

Nor can the tsar hire qualified labor in Europe: Hans Schlitte, the agent of Tsar Ivan IV, had in 1547 employed craftsmen in Germany for work in Russia, but all these craftsmen had been arrested in Lübeck at the request of Livonia.

The German Hanseatic League has ignored the new Ivangorod port built in 1550 by Tsar Ivan on the eastern shore of the Narva River and continues to trade with the ports owned by Livonia.

Competition for the Baltic coast with Sweden had escalated into open war in 1554, interrupted only by a fragile truce in March 1557.

Ivan now demands that the Livonian Confederation pay forty thousand thalers for the Bishopric of Dorpat, based on a claim that the territory had once been owned by the Russian Novgorod Republic.

The federation turns to the Polish-Lithuanian union in the Treaty of Pozvol; Ivan regards this as casus belli.

The dispute ends with a Russian invasion in 1558.

Russian troops occupy Dorpat (Tartu) and ...

... Narva, ...

...laying siege to Reval (Tallinn).

Ivan’s goal is the vital access to the Baltic Sea.

Transylvania’s 1558 Diet of Turda declares free practice of both the Catholic and Lutheran religions, but prohibits Calvinism.

Sinan, the prolific Turkish architect, engineer, and town planner, builds the Süleymaniye Mosque in Constantinople from 1550 to 1558.

Sinan considers the design to be an architectural counterpoint to the Byzantine Hagia Sophia, converted under Mehmed II into a mosque that serves as a model to many Ottoman mosques in Istanbul.

Sinan's Süleymaniye is however a more symmetrical, rationalized and light-filled interpretation of earlier Ottoman precedents, as well as the Hagia Sophia, though it is smaller in size than its older archetype.

Located on the second Hill of Istanbul, it is today the city's second largest mosque and one of its best-known sights.

The Portuguese establish a fortified factory settlement at Daman in 1558.

The coastal enclaves of Daman and Diu on the Arabian Sea coast will be part of Portuguese India, along with Goa and Dadra and Nagar Haveli, for over four hundred and fifty years.

The treaty between Vijayanagara and Portugal is broken in 1558, and Rama Raya now exacts tribute in compensation for damage to temples caused by the Portuguese.

The Ottomans make Massawa the capital of Habesh, a province that had been proclaimed in 1554, preceded by several generations of conflict between the Ottomans, who had been primarily concerned with Anatolia and Eastern Europe, and the Portuguese, who are the major power in the Red Sea and the Indian Ocean.

Due to resistance, as well as sudden and unexpected demands for more troops in the Mediterranean and on the border with Persia, the Ottoman authorities place the city and its immediate hinterlands under the control of one of the aristocrats of the Bellou people, whom they appoint Naib of Massawa and make answerable to the Ottoman governor at Suakin.

The Ottomans nevertheless build the old town of Massawa on Massawa Island into a prominent port on the Red Sea in typical Islamic Ottoman architecture, using dry corals for walls, roof and foundation as well as imported wood for beams, window shutters and balconies.

These buildings and the old town of Massawa remain to this day, despite having withstood both earthquakes and wars with aerial bombardment.

The three-volume Historiae Animalium, published by Swiss physician and naturalist Conrad Gessner from 1551 to 1558, is considered the beginning of modern zoology, and the flowering plant genus Gesneria (Gesneriaceae) is named after him.