[2][4] In mid-1857, Radetzky, her sister ship Adria, and the screw corvette Erzherzog Friedrich went on a training cruise in the North and Baltic Seas.

They stopped in Hamburg; Danzig, Prussia; Copenhagen, Denmark; and Karlskrona, Sweden, but they avoided British and French ports on their way to and from the Baltic, and did not continue on to visit Russia either; all three countries were still resentful of Austria's failure to enter the Crimean War on either the Anglo-French or Russian sides.

[5] 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.

[7] In late 1862, the head of the Austrian Navy, Archduke Ferdinand Max, offered the sale Radetzky and several other wooden ships in an attempt to acquire funds to build a fleet of ironclad warships, though the proposal came to nothing.

At the time, the Danish fleet was far superior to the Prussian naval forces initially available, which allowed the Danes to blockade the German coast.

[9][10] On the morning of 9 May, Tegetthoff learned that a Danish squadron consisting of the steam frigates Niels Juel and Jylland and the corvette Hejmdal were patrolling off the island of Heligoland.

After Schwarzenberg caught fire, Tegetthoff broke off the action and escaped to the neutral waters around Heligoland, where the ships remained until early the next day.

Though the Danish squadron had won a tactical victory at Heligoland, the arrival of Austrian warships in the North Sea forced the Danes to withdraw their blockade.

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.

Radetzky 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 ironclad warships.

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.