Thus, for half a millennium, the battle was referred to as

* Schlacht bei Tannenberg (Battle near Tannenberg) by Germans
* Bitwa pod Grunwaldem (Battle of Grunwald) by Poles
* Žalgirio mūšis (Battle of Žalgiris) by Lithuanians

In languages of other involved nations the battle is called: Belarusian: Гру́нвальдзкая
бі́тва, Hrúnvaldzkaja bі́tva, Ukrainian: Ґрю́нвальдська би́тва, Gryúnvaldska býtva,
Russian: Грю́нвальдская би́тва, Gryúnvaldskaya bі́tva, Tatar: Grünwald suğışı, Czech:
Bitva u Grunvaldu, Romanian: Bătălia de la Grünwald.

In the 13th century, the Teutonic Knights, subject directly to the Pope, had been requested
by Konrad of Masovia to come to the lands surrounding Culm (Chełmno) to assist in the Crusade
against the pagan Prussians. The Teutonic Order received the territory of Prussia via golden
bulls from the Emperor and papal edict, which gave them effective carte blanche as owners of
a new Christianized state in the region. They later received the territory of further north
Baltic coastal regions of what are now Latvia, Lithuania and Estonia, and showed every sign
of further expansion.

In 1385 the Union of Kreva joined the Crown of Poland and Lithuania, and the subsequent
marriage of Grand Duke Jogaila of Lithuania and reigning Queen Jadwiga of Poland was to
shift the balance of power; both nations were more than aware that only by acting together
could the expansionist plans of the Teutonic Order be thwarted. Jogaila accepted Christianity
and became the King of Poland as Władysław Jagiełło. 

In 1409, an uprising in Teutonic-held Samogitia started. The King of Poland and Grand Duke
of Lithuania announced that he would stand by his promises in case the knights invaded
Lithuania. This was used as a pretext, and on 14 August 1409 the Teutonic Grand Master Ulrich
von Jungingen declared war on the Kingdom of Poland and Grand Duchy of Lithuania. The forces
of the Teutonic Order initially invaded Greater Poland and Kuyavia, but the Poles repelled the
invasion and reconquered Bydgoszcz (Bromberg), which led to a subsequent armistice agreement
that was to last until 24 June 1410. The Lithuanians and Poles used this time for preparations
to remove the Teutonic threat once and for all.

The forces of the Teutonic Knights were aware of the Polish-Lithuanian build-up and expected
a dual attack, by the Poles towards Danzig (Gdańsk) and by the Lithuanians towards Samogitia.
To counter this threat, Ulrich von Jungingen concentrated part of his forces in Schwetz (Świecie)
while leaving the large part of his army in the eastern castles of Ragnit (Ragainė), Rhein (Ryn)
near Lötzen (Giżycko), and Memel (Klaipėda). Poles and Lithuanians continued to screen their
intentions by organising several raids deep into enemy territory. Ulrich von Jungingen asked for
the armistice to be extended until July 4 to let the mercenaries from western Europe arrive.
Enough time had already been given for the Polish-Lithuanian forces to gather in strength.

On 30 June 1410, the forces of Greater Poland and Lesser Poland crossed the Vistula over a
pontoon bridge and joined with the forces of Masovia and the Grand Duchy of Lithuania. Jogaila's
Polish forces and the Lithuanian soldiers of his cousin Grand Duke of Lithuania Vytautas the Great
(to whom Jogaila had ceded power in Lithuania in the wake of his marriage to the Polish queen)
assembled on 2 July 1410. A week later they crossed into the territory of the Teutonic Knights,
heading for the enemy headquarters at the castle of Marienburg (Malbork). The Teutonic Knights
were caught by surprise.

In the early morning of 15 July 1410, both armies met in the fields near the villages of Grunwald,
Stębark (Tannenberg) and Łodwigowo (Ludwigsdorf). Both armies were formed in opposing lines. The
Polish-Lithuanian army was positioned in front and East of the villages of Ludwigsdorf and Tannenberg.
The left flank was guarded by the Polish forces of king Władysław Jagiełło and composed mostly of
heavy cavalry. The right flank of the allied forces was guarded by the army of Grand Duke Vytautas,
and composed mostly of light cavalry. Among the forces on the right flank were banners from all over
the Grand Duchy, as well as Tatar skirmishers under Jalal ad-Din khan, Moldovan light cavalry sent
by Alexandru cel Bun and allegedly Serbs. The opposing forces of the Teutonic Order were composed
mostly of heavy cavalry and infantry. They were to be aided by troops from Western Europe called
"the guests of the Order", who were still on the way, and other Knights who had been summoned to
participate by a Papal Bull.

The exact number of soldiers on both sides is hard to estimate. There are only two reliable sources
describing the battle. The best-preserved and most complete account, Banderia Prutenorum, was written
by Jan Dlugosz, but does not mention the exact numbers. The other is an incomplete and preserved
only in a brief 16th century document. Months after the battle, in December 1410, the Order's new
Grand Master Heinrich von Plauen the Elder sent letters to Western European monarchs in which he
described the battle as a war against the forces of evil pagans. This view was shared by many chronicle
writers. Since the outcome of the battle was subject to propaganda campaigns on both sides, many
foreign authors frequently overestimated the Polish-Lithuanian forces in an attempt to explain the result.

In one of the Prussian chronicles it is mentioned that "the forces of the Polish king were so numerous
that there is no number high enough in the human language". One of the anonymous chronicles from the
German Hanseatic city of Lübeck mentions that the forces of Jogaila numbered some 1,700,000 soldiers,
the forces of Vytautas with 2,700,000 (with a great number of Russians, or Ruthenians, as they were
called then), in addition to 1,500,000 Tatars. Among the forces supposedly aiding the King of Poland and the
Polish-Lithuanian army were "Saracens, Turks, pagans of Damascus, Persia and other lands". According to
Enguerrand de Monstrelet, the knights fielded some 300,000 men, while their enemies under the kings of
"Lithuania, Poland and Sarmatia" fielded 600,000. Andrew of Regensburg estimated the Polish-Lithuanian
forces at 1,200,000 men-at-arms. It must be noted that medieval chroniclers were notorious for
sensationally inflating figures, and armies of the sizes quoted were actually impossible with the
logistics technology of the day.

The overall commander of the joint Polish-Lithuanian forces was king Jagiełło, with the Polish units
subordinated to Marshal of the Crown Zbigniew of Brzezie and Lithuanian units under the immediate
command of Grand Duke of Lithuania Vytautas the Great. Until recently it was believed that the Sword
Bearer of the Crown Zyndram of Maszkowice was the commander in chief of the joint army, but this idea
was based on a false translation of the description of the battle by Ioannes Longinus. The Teutonic
Forces were commanded directly by the Grand Master of the Order Ulrich von Jungingen.

The opposing forces formed their lines at dawn. At about noon the forces of Grand Duke of Lithuania
Vytautas started an all-out assault on the left flank of the Teutonic forces, near the village of
Tannenberg (Stębark). The Lithuanian cavalry was supported by a cavalry charge of several Polish
banners on the right flank of the enemy forces. The enemy heavy cavalry counter-attacked on both
flanks and fierce fighting occurred.

After more than an hour, the Lithuanian light cavalry started a retreat towards marshes and woods.
This maneuver was often used in the east of Grand Duchy of Lithuania by Mongols. Vytautas, who had
experience in battles against Mongols, used it in this battle. Only three banners of Smolensk
commanded by Lengvenis (Simon Lingwen), son of Algirdas, brother of Jogaila and a cousin of Vytautas,
remained on the right flank after the retreat of Vytautas and his troops. One of the banners was
totally destroyed, while the remaining two were backed up by the Polish cavalry held in reserve and
broke through the enemy lines to the Polish positions.

Heavy cavalry of the Order started a disorganised pursuit after the retreating Lithuanians.
The Knights entered the marshes, while Vytautas reorganized his forces to return to battle.
At the same time heavy fighting continued on the left flank of the Polish forces. After
several hours of massed battle, the Teutonic cavalry started to gain the upper hand. According
to Ioannes Longinus the Grand Master Ulrich von Jungingen personally led a cavalry charge
on the strongest Polish unit - the Banner of the Land of Kraków. The Polish ranks started to
waver and the flag of the banner was lost. However, it was soon recaptured by the Polish
knights, and King Jogaila ordered most of his reserves to enter combat. The arrival of fresh
troops allowed the Poles to repel the enemy assault and the forces of Ulrich von Jungingen
were weakened. At the same time his reserves were busy pursuing the evading Lithuanian cavalry.

A pivotal role in triggering the Teutonic retreat is attributed to the leader of the banner of Chełmno
(Culm), Nikolaus von Renys (Mikołaj of Ryńsk), born in Prussia (identified by Longinus as Swabia). The
founder and leader of the Lizard Union, a group of Order Knights sympathetic to Poland, refused to fight
the Polish. Lowering the banner he was carrying was taken as a signal of surrender by the Teutonic troops.
Accused of treason, ultimately von Renys was beheaded by his order, along with all of his male descendants.

After several hours of fighting, Ulrich von Jungingen decided to join his embattled forces in the main
line of engagement. At this time, however, Vytautas returned to the battlefield with the reorganized
forces of the Grand Duchy of Lithuania and joined the fierce fighting. The Teutonic forces were by
then becoming outnumbered by the mass of Polish knights and the advancing Lithuanians cavalry, which
all of a sudden had come pouring on the battlefield from the surrounding forests.

Ulrich von Jungingen personally led the assault with 16 banners of heavy cavalry, which until then were
held in reserve. Jogaila, however, threw in all his remaining reserves, as well as several already tired
units. Putting up heavy resistance, the 16 banners of the Grand Master were surrounded and began to suffer
high losses, including the Grand Master himself. Seeing the fall of their Grand Master, the rest of the
Teutonic forces started to withdraw towards their camp.

Part of the routed units retreated to the marshes and forests where they were pursued by the Lithuanian
and Polish light cavalry, while the rest retreated to the camp near the village of Grunwald, where they
tried to organise the defence by using the tabor tactics: the camp was surrounded by wagons tied up with
chains, serving as a mobile fortification. However, the defences were soon broken and the camp was looted.
According to the anonymous author of the Chronicle of the Conflict of Ladislaus King of Poland with the
Teutonic knights Anno Domini 1410, there were more bodies in and around the camp than on the rest of the
battlefield. The pursuit after the fleeing Teutonic cavalry lasted until the dusk.

 

After the battle Polish and Lithuanian forces stayed on the battlefield for three days. All notable officials
were interred in separate graves, while the body of Ulrich von Jungingen was covered with royal coat and
transported to Marienburg Castle. The rest of the dead were gathered in several mass graves. There are
different speculations as to why Jogaila decided to wait that long. After three days, the Polish-Lithuanian
forces moved on to Marienburg and laid siege upon the castle, but the three days time had been enough for
the knights to organise the defence. Troops from Livonia were expected to support their brothers, and the
ongoing conflict with Sigismund of Luxemburg could cause problems elsewhere. After several weeks of siege,
the Lithuanian Grand Duke withdrew from the war and it became clear that the siege would not be effective
The nobility from Lesser Poland also wanted to end the war before the harvest, and the siege was lifted.

In the battle, both Polish and Lithuanian forces had taken several thousand captives. Most of the mercenaries
were released shortly after the battle on the condition that they will return to Kraków on 29 September 1410.
After that move, the king held most of the Teutonic officials, while the rest returned to Prussia to beg the
Teutonic Order officials for their liberation and ransom payment. This proved to be a major drain of the
Teutonic budget as the value of a Teutonic Knight was quite high.

According to the Peace of Thorn signed in February 1411, the Order had to cede the Dobrin Land (Dobrzyń Land)
to Poland, and resign their claims to Samogitia for the lifetime of the king. This is thought to be a diplomatic
defeat for Poland and Lithuania as they pushed for attempts to dismantle the Monastic state of the Teutonic
Knights altogether. However, while the Poles and Lithuanians were unable to translate the military victory in
the battle to greater geographical gains, the financial consequences of the peace treaty were much worse for
the knights, having to pay about 5 tons of silver in each of the next four years.