Upon the invitation of Duke Konrad I of Masovia, the Teutonic Knights took possession of Prussia in the 13th century and created a monastic state to administer the conquered Old Prussians. Local Old-Prussian (north) and Polish (south) toponyms were gradually Germanised. The Knights' expansionist policies, including occupation of Polish Pomerania with Gdańsk/Danzig and western Lithuania, brought them into conflict with the Kingdom of Poland and embroiled them in several wars, culminating in the Polish-Lithuanian-Teutonic War, whereby the united armies of Poland and Lithuania, defeated the Teutonic Order at the Battle of Grunwald (Tannenberg) in 1410. Its defeat was formalised in the Second Treaty of Thorn in 1466 ending the Thirteen Years' War, and leaving the former Polish region Pomerania/Pomerelia under Polish control. Together with Warmia it formed the province of Royal Prussia. Eastern Prussia remained under the Knights, but as a fief of Poland. 1466 and 1525 arrangements by kings of Poland were not verified by the Holy Roman Empire as well as the previous gains of the Teutonic Knights were not verified.
Which group took possession of Prussia in the 13th century?
Teutonic Knights

By 1353, the three original cantons had joined with the cantons of Glarus and Zug and the Lucerne, Zürich and Bern city states to form the "Old Confederacy" of eight states that existed until the end of the 15th century. The expansion led to increased power and wealth for the federation. By 1460, the confederates controlled most of the territory south and west of the Rhine to the Alps and the Jura mountains, particularly after victories against the Habsburgs (Battle of Sempach, Battle of Näfels), over Charles the Bold of Burgundy during the 1470s, and the success of the Swiss mercenaries. The Swiss victory in the Swabian War against the Swabian League of Emperor Maximilian I in 1499 amounted to de facto independence within the Holy Roman Empire.
By 1460, who controlled most of the territory south and west of the Rhine?
the confederates

During the September 11, 2001 attacks on the World Trade Center, FBI agent Leonard W. Hatton Jr. was killed during the rescue effort while helping the rescue personnel evacuate the occupants of the South Tower and stayed when it collapsed. Within months after the attacks, FBI Director Robert Mueller, who had been sworn in a week before the attacks, called for a re-engineering of FBI structure and operations. He made countering every federal crime a top priority, including the prevention of terrorism, countering foreign intelligence operations, addressing cyber security threats, other high-tech crimes, protecting civil rights, combating public corruption, organized crime, white-collar crime, and major acts of violent crime.
What FBI agent was killed during attacks on the World Trade Center?
Leonard W. Hatton Jr