In 1808 and early 1809 he was stationed on the Scheldt, where Danes crewed and officered Pultusk (or Pulstuck) and Dantzick, two French ships-of-the-line.

[4] When the Danish captains were replaced on 28 January 1809 with French ones, Falsen and fellow officer Senior Lieutenant Frederick Christian Holsten[5] resigned in protest and refused to obey orders, so they were arrested and sent to Frederickshavn Citadel to serve a six-month detention.

In July 1809 Falsen was posted to a gunboat flotilla in the Great Belt, but in August was ordered from Nyborg to Fladstrand.

[6] In an engagement lasting some ninety minutes, Falsen's flotilla of four gunboats exchanged heavy fire with a British frigate of 32 guns on 27 April 1810 off Skagen (The Skaw) before both sides broke off the fight.

In early 1811, now the officer commanding Fladstrand and Hals[Note 2] flotilla, the prize money that was owed to him was finally given.

In November 1811 Falsen was off sick due to his battle wounds worsening, but on 19 August 1812 he was again involved in an action when he captured the brig HMS Attack off Grenå.

He continued to suffer from liver disease and gallstones, but eventually retired from the Danish navy at the rank of counter admiral in 1848.