War with Russia (1501–1503) In 1500, Plettenberg made an alliance with the
Grand Duke of Lithuania,
Alexander Jagiellon (the Treaty of
Wenden), who had been at war with Russia since 1499. He also tried to convince
Pope Alexander VI to issue a
crusading bull against the Russians in order to acquire funding from the sale of
indulgences, but his efforts were in vain. In the war with Russia (1501–1503), Plettenberg showed himself to be a talented and skilled commander. His strength lay in his skillful use of heavy
cavalry and
artillery fire. With such tactics Plettenberg won the
Battle of the Siritsa River (August 1501), where an army of the Livonian Confederation of 8,000 foot and 4,000 horse defeated a roughly twice as large Russian army. However, an outbreak of
dysentery in Plettenberg's army prevented him from exploiting this success. A subsequent defeat at the Battle of
Helmet and the unsuccessful siege of
Pskov followed. Without the promised help of the Lithuanians, Plettenberg was unable to conquer Pskov and only burned the stronghold of
Ostrov. During the winter of 1501–1502, the Russians harshly ravaged Eastern Livonia and many Livonian dignitaries wanted to make peace with
Muscovy. But Plettenberg decided to continue the war and attempted to conquer Pskov one more time. However, due to Moscow's strong support of Pskov, he was forced to retreat southwest from the city. On 13 September 1502, he won the
Battle of Smolin (at Lake Smolin close to the village Palkino in
Pskov Oblast) with his 5,000 men against about 12,000 Russians. The next day, 14 September, became the Victory Day in Livonia.
Diplomacy and Peace (1503–1535) In 1503, peace between
Ivan III and Livonia on the terms of
status quo ante bellum was concluded. Due to the lack of Lithuanian support, Plettenberg achieved only a six-year peace treaty from Moscow, though it was renewed in 1509, 1521, and 1531. Plettenberg succeeded in maintaining Livonian neutrality in the ongoing conflicts between Poland-Lithuania and Muscovy from 1503 onwards, refusing to commit too heavily to either side in order not to endanger Livonia's independence. Through military self-assertion and diplomatic restraint, he protected the country from renewed Russian aggression for more than half a century—the peace he established lasted nearly 60 years until the outbreak of the Livonian War in 1558, more than two decades after his death.
Relations with the Teutonic Order in Prussia and Territorial Gains (1519–1525) Plettenberg also skillfully managed relations with the Teutonic Order in
Prussia. When Grand Master
Albert von Brandenburg-Ansbach attempted to recruit Livonia for his planned war against Poland (1519–1521), Plettenberg refused, preserving peace for Livonia and maintaining independence from the Order's policies in Prussia. In 1525, taking advantage of Albert's financial difficulties following his conversion to Protestantism and secularization of the Prussian branch of the Order, Plettenberg brought the northern Estonian territories of
Harju County ("Harrien") and
Virumaa ("Wierland"), including the city of
Tallinn ("Reval"), under his direct control. These territories had previously been under the sovereignty of the
Grand Master in Prussia, and their acquisition significantly strengthened Plettenberg's position.
Reformation in Livonia (1521–1526) ) During the
Protestant Reformation, which reached Livonia in 1521–1522, Plettenberg faced a complex political and religious situation. The Livonian confederation lacked a central authority and included diverse actors with different stances toward the Reformation: the Church with its dioceses and monasteries, cities tied to the Hanseatic League, the knighthood, and the Teutonic Order itself, along with various international powers seeking to expand their influence. Fearing violence and foreign intervention in the fragmented confederation, Plettenberg pragmatically decided to allow Livonian churches to conduct services in the
Lutheran manner from 1522 onwards. This decision enabled the bloodless introduction of the Reformation among Germans, Estonians, and Latvians in Livonia. However, Plettenberg himself remained
Catholic throughout his life, deeply rooted in his traditional faith and the Order's allegiance to the Catholic Emperor and
Pope. In 1525–1526, he rejected conversion to Lutheranism and secularization of the Livonian Order, despite considerable pressure from multiple sources: the city of Riga, Grand Master Albert von Brandenburg-Ansbach (who had converted to Protestantism and secularized the Prussian branch of the Order), and even the Hanseatic League, which consequently rejected an alliance with Plettenberg at the general Hanseatic Diet in
Lübeck. Plettenberg also imprisoned Archbishop of Riga
Thomas Schöning in
Ronneburg Castle when the archbishop appealed to the Grand Duke of Moscow for help, demonstrating his determination to prevent foreign interference in Livonian affairs. == Prince of the Holy Roman Empire (1526–1530) ==