[3][4] The battle was part of a campaign in spring 1837 when the liberal Army tried to chase the Carlists from the Basque Country.

[5] It was planned that the British-Spanish force, starting at San Sebastián, led by George de Lacy Evans would attack the Carlist-held Hernani.

[1] On 15 March the British Auxiliary Legion conquered a fortification known as Oriamendi on a strategic hill near San Sebastián.

[3] The next day the Carlists under Sebastian de Borbón counterattacked and routed the liberal forces supported by the British Legion, both of which suffered heavy losses.

[citation needed] This force had suffered between 1,000 and 1,500 casualties and covering fire from the Royal Navy prevented the withdrawal from becoming a disaster.