He was born on 26 January 1836 in Copenhagen, and his parents were Niels Georg la Cour (no. 13) and Emilie Antoinette la Cour. Following in his father’s footsteps, Eugen was enrolled at the Landkadetakademi* army military academy as a child and became a cadet in 1851, attaining the rank of second lieutenant in 1853. From 1 March 1853 to 1 November 1854, he worked as an assistant instructor in that same institution. He was subsequently recruited by the 7th Battalion, serving with them in Copenhagen but transferring to Sønderborg on 20 April 1861.
Eugen remained with the 7th Battalion during the Second Schleswig War*, most notably fighting in the Battle of Dybbøl on
18 April 1864, and was promoted to first lieutenant on 23 April 1864. After the war, he remained in Svendborg and Fåborg, but was transferred to the 14th Battalion on 17 November 1864 and stationed first in Viborg and later in Aalborg. When this
battalion was temporarily disbanded on 1 May 1866, Eugen was transferred to the 18th Battalion in Copenhagen and then, from 20 April 1868, in Helsingør (Elsinore). On 1 April 1872 he was sent to serve with the 1st Battalion in Copenhagen, but after being promoted to captain in 1875, he went to the 22nd Battalion in Helsingør. He was then transferred, on 10 July 1876, to the 3rd Battalion, also in Helsingør. In this period he fathered two children out of wedlock: their mother was
Ida Elvina Cathrine Mogensen, a woman born in Rudkøbing on 23 February 1841, who at the time lived in Frederiksberg.
At his own request, Eugen was made a company commander with the 5th Battalion (in Odense) in 1878, transferred to the 7th Battalion (in Nyborg) in 1880 and then moved to the 13th Battalion (in Copenhagen) in 1887, having already been made a Knight of the Order of Dannebrog* in 1883. Placed at the disposal of the 3rd Regiment (Copenhagen) in 1887, Eugen was honourably discharged in 1888 with a pension due to age. Afterwards, he remained in Copenhagen and was a highly active member of a charitable company called Kjæden. He received a new certificate of discharge as a lieutenant colonel in 1891.
In July 1897, Eugen he took a six-month trip to France, especially Paris. From 1889 to 1899, he made several trips abroad and visited most of the European countries, in 1898 and 1899 also travelling to North Africa, Egypt and the Holy Land. He died on 20 January 1900 in Copenhagen after a very short period of illness and left a small fortune to a family scholarship for the benefit of his brothers and their descendants. (Two children: the Frederiksberg Line.)