A 16th-century ceremonial shield displayed at the Philadelphia Museum of Art since 1976 as part of the museum’s arms and armor collection was stolen during World War II by the Nazis from what was then Czechoslovakia and carried away to Austria to help satisfy the Führer’s personal desire for a grand cultural temple, according to museum and Czech officials.

The elaborately decorated “pageant shield,” which came to the PMA as part of the coveted Carl Otto Kretzschmar von Kienbusch Collection in 1976 and was once owned by Archduke Franz Ferdinand, whose assassination in 1914 helped trigger World War I, will now be returned to the Czech Republic, its rightful owner, the officials said on Monday in announcing a restitution agreement between the museum and the republic.

Timothy Rub, chief executive and director of the museum, said the decision to return the shield, which depicts the chaotic Roman storming of New Carthage in 209 B.C., comes after a five-year investigation by the museum and Czech historians and cultural officials at the Czech National Heritage Institute in Prague.

That investigation, Rub said, firmly established the identity and origin of the shield, made about 1535 and bearing intricate painted decoration attributed to Girolamo di Tommaso da Treviso (c. 1497-1544), based on a design by the painter Giulio Romano (Italian, 1492/99-1546). The shield is made of wood, linen, gesso, gold, and pigment and is 24 inches in diameter. It has been deaccessioned and is no longer on display; it will be returned to the Czech Republic soon, officials said.

Archduke Franz Ferdinand, who maintained a vast collection of arms and armor, was heir to the Austro-Hungarian Empire; he displayed the collection, including the pageant shield, at his grand country residence, Konopiště Castle, near Prague.

After the Austro-Hungarian defeat in the war, former imperial Habsburg properties were redistributed, and in 1919, Konopiště Castle and its collections became the property of the government of the newly formed nation of Czechoslovakia.

Just 20 years later, however, the Nazi government annexed the part of Czechoslovakia where Konopiště Castle was located, and in 1943, the German army confiscated the Konopiště Castle armor collection, including the shield, taking all to Prague to be housed in a new military museum.

But Adolf Hitler’s arms and armor curator, Leopold Ruprecht, soon skimmed off the cream of the collection, inventoried it, and dispatched it to Vienna, intending the best for Hitler’s planned mega-museum in Linz, Austria — the so-called Führermuseum, never realized.

At the war’s conclusion, the allies recovered many Konopiště artifacts and returned them to Czech authorities. About 15 artifacts remained unidentified.

Recent research and, in particular, a photograph from about 1913 showing the shield displayed at Konopiště Castle, have now served persuasively to identify the shield in the PMA armor collection as the one looted from Konopiště Castle by the Nazis during the war.

At its June meeting, the Art Museum board of trustees approved deaccessioning the shield from the museum collection and returning it to the Czech Republic.

After eight decades the shield will finally return home, to the place where it had been decorating the Konopiště Castle for many years,” Lubomír Zaorálek, minister of culture of the Czech Republic, said Monday in a statement.Justice prevailed over the despotism of the Nazi regime, which illegally alienated this precious artifact that dates back to the beginning of the 16th century.”

Rub said that Kienbusch, who bestowed his armor collection on the PMA in 1976, purchased the shield in August 1954 from its then-owner, Theodore Wollner. Wollner had put the shield up for auction in April of that year but it failed to sell.

Nothing more is known about the movement of the shield after the end of the war, said Rub. It was discovered at the PMA in 2016 by a Czech historian researching Konopiště Castle artifacts. That discovery led to Monday’s announcement and the restitution of the shield to the Czech Republic.

In a statement, Naděžda Goryczková, the general director of the National Heritage Institute, said the institute looked forward to both the return of the shield and “a fruitful collaboration between the Philadelphia Museum of Art and the National Heritage Institute in the field of restoration, conservation, and presentation of artworks.”

Hynek Kmoníček, ambassador of the Czech Republic to the United States, lauded both the museum’s cooperation in the lengthy investigation and its stewardship of the shield over the decades.

“This case is a prime example of best practices in restitution,” Kmoníček said.