[1] In early 1859, tensions between Austria and the Kingdom of Sardinia rose significantly, prompting the Austrian government to order the fleet to mobilize in February to be prepared for an attack by the Royal Sardinian Navy.

They did not sortie to attach the French or Sardinian naval forces, and the war ended quickly after the defeats at Magenta and Solferino in June.

As the fleet made its preparations, the ships carried out extensive practice in the Fasana Channel, which was protected from an Italian attack by naval mines.

Adria and the other wooden vessels were fitted with iron chains that draped down over the sides of their hulls to give them a degree of protection for the coming fight with Italy's larger fleet of ironclads.

Tegetthoff initially believed the attack to be a feint to draw his fleet away from Venice and Trieste, but by the 19th, it had become clear that the Italians intended to land on the island.

[4] The second line, led by Kommodore Anton von Petz aboard Kaiser, also included Donau's sister ships, the screw frigates Schwarzenberg and Novara, and Erzherzog Friedrich.

[6] In October 1868, Donau and Erzherzog Friedrich sailed from Trieste on a major voyage to Siam, China, and Japan to negotiate trade treaties with those countries.

The two ships were commanded by Petz, and they sailed south, around Africa, and then crossed the Indian Ocean on their way to East Asia.

Donau, meanwhile, continued on across the Pacific, and while at sea in late November, she was struck by another typhoon that damaged her rigging, destroyed her rudder, and left her badly leaking.

By the time the new rudder was ready to be installed, the ship had traveled some 600 nautical miles (1,100 km; 690 mi) with little ability to steer.

It was estimated that the project would be complete by late April 1870, so Petz decided to use the time to travel via steamer to Guatemala, Peru, Chile, Argentina, and Uruguay to negotiate trade agreements.

Donau entered the dangerous Strait of Magellan on 14 September, and she was forced to anchor in Fortescue Bay the following night.

She remained in Punta Arenas to weather a severe storm in late September, and by 3 October, she had reached Montevideo, Uruguay.