Background
He was born in Holmestrand as the son of ship-owner Nils Ihlen (1793–1865) and Barbara Wincentz Thurmann (1800–1879).
He was born in Holmestrand as the son of ship-owner Nils Ihlen (1793–1865) and Barbara Wincentz Thurmann (1800–1879).
He finished his secondary education in 1851 and took the candidate.jur. degree in 1855. After working three years as a trainee in a trading company, he was an attorney in Christiania from 1859, and a barrister with access to working with Supreme Court cases from 1863. He was elected to the Parliament of Norway in 1883, and re-elected in 1886, representing the urban constituency of Kristiania, Hønefoss og Kongsvinger.
From 1871 to 1903 he chaired Forsikringsselskapet Poseidon.
He died in 1903 in Kristiania.
He was a member of Kristiania city council from 1872. He was also a deputy board member of Hypothekbanken from 1888.