Tegetthoff attacked with his two frigates while the slower Prussian vessels lagged behind, unable to effectively engage the Danish warships.

By the time fighting broke out again in June, further Austrian warships had arrived to strengthen the Austro-Prussian naval forces, and the Danes did not seek to challenge them.

Historians' opinions on the outcome of the battle are mixed, with some citing the withdrawal of Tegetthoff's ships, and the greater damage they sustained, as evidence of a tactical victory for Suenson.

Other naval historians cite the lifting of the blockade as a strategic victory for the Austrians and Prussians, and others still describe the battle as inconclusive.

[1] The crisis erupted in the Second Schleswig War, which began on 1 February 1864, after the Prussian and Austrian Empires delivered an ultimatum to Denmark to cede the disputed duchies to Austro-Prussian control.

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.

Also in the Mediterranean were the Prussian aviso SMS Preussischer Adler and the gunboats Blitz and Basilisk; these vessels were immediately recalled to German waters.

The Levant Squadron, centered on Schwarzenberg and Radetzky arrived in the North Sea on 1 May; Tegetthoff's other two vessels, the corvette Dandolo and the gunboat Seehund, were unavailable due to boiler trouble and a grounding, respectively.

The Austrian and Prussian squadrons rendezvoused in Texel, the Netherlands, and Tegetthoff added Preussischer Adler, Blitz, and Basilisk to his force.

The two squadrons, in line ahead formation with the Prussian vessels lagging behind, closed to about 1,800 m (2,000 yd) and passed in opposite directions, firing broadsides at each other.

As Tegetthoff's ships began to withdraw, one of them scored a hit on Jylland's rudder, which prevented Suenson from being able to effectively pursue the retreating Austrians and Prussians.

[12] Suenson waited outside the British zone of 3 nautical miles (5.6 km), but the Austrian-Prussian squadron was able to escape during the night to Cuxhaven, arriving at about 04:00 on 10 May.

These advances, coupled with the capture of the island of Als in the Baltic Sea, forced the Danes to seek a second armistice on 29 June.

[17] John Greene and Allesandro Massignani state that "Heligoland was Tegetthoff's day", though noting that Suenson could have won a victory had Jylland not been rendered unmaneuverable at the end of the action.

[15] On the other hand, David Zabecki affirms the argument that the battle "was a tactical Danish victory", while noting the lifting of the blockade.