A spectacular view of a German fortress by the 18th-century Italian artist Bernardo Bellotto, nephew of the far more famous Canaletto, has been acquired by the National Gallery after an appeal raised almost £12m to save it from export.

The government placed a temporary export bar because of the painting’s historical importance and the centuries it had spent in British collections to allow a UK institution time to match the sale price. The National Gallery raised the £11.7m through donations from individuals and trusts, including $6.5m (£5m) from the American Friends of the gallery and a £550,000 grant from the Art Fund.

Gabriele Finaldi, director of the gallery, called it a truly significant acquisition. “This superb painting which has been saved for the nation shows Bellotto as one of the greatest view painters of his time.”

The sweeping landscape of The Fortress of Königstein from the North, which measures 132cm by 236cm, was originally one of five monumental views of the castle near Dresden commissioned by Augustus III, King of Poland and Elector of Saxony, a notably ineffective ruler but a significant patron of the arts.

Bellotto, who began his career as a painter of Venetian scenes like his uncle, became better known for his northern views. He was court painter to Augustus, but all five paintings ended up in Britain because by the time they were complete the seven years war had torn up the map of Europe. One is now in the National Gallery of Art in Washington, two are in Manchester Art Gallery and the remaining pair were in the Earl of Derby’s family collection at Knowsley Hall until this one was sold through Christie’s to an overseas buyer 18 months ago, prompting the export bar.

Stephen Deuchar, director of the Art Fund, said: “The acquisition of this masterpiece of grand European topography is an important save for the nation’s collections.”

There are only 13 paintings by Bellotto in UK public collections, almost all Italian views, and most of the National Gallery’s scores of 18th-century view paintings are also of Italian scenes. The Fortress, under a colder German sky, goes on display in a special exhibition at the National Gallery from Tuesday, and will then be hung with works by his uncle and other Venetian painters.