This section does not cite any sources
. (September 2014)
The British government feared the powerful Danish fleet was about to fall into French hands and thus delivered Denmark an ultimatum to sail its fleet to Britain or face war with Britain. The Danes refused to sail it to Britain and so British troops landed at Vedbæk on 16 August and began to bombard Copenhagen. Generalløjtnant Castenschiold was ordered to create a frikorps and rescue Copenhagen.
Castenschiold's forces concentrated themselves around Roskilde and Lejre, while general Oxholm was sent south to activate the Søndre Sjællandske Landeværnsregiment. Castenschiold arrived at Køge on 26 August and two days later he was joined by Oxholm and his force. This gave Castenschiold a grand total of around 7,000 militiamen, 600 cavalry and 13 cannon. In the meantime the British headquarters at Copenhagen had gained had become aware of the Danish militia's mobilisation and on 27 August general Arthur Wellesley (later 1st Duke of Wellington) was ordered to find and defeat it.