At that juncture the first Carlist War broke out, and Lambermont hastened to the scene of action to support catholicism and absolutism.

He was one of the first Belgians to see the importance of developing the trade of their country, and at his own request he was attached to the commercial branch of the foreign office.

Twenty-one powers and states attended a conference held on the question at Brussels in 1863, and on 15 July the treaty freeing the Scheldt was signed.

He was joint reporter with Baron Alphonse Chodron de Courcel of the Berlin Conference in 1884-1885, and on several occasions he was chosen as arbitrator by one or other of the great European powers.

But his great achievement was the freeing of the Scheldt and in token of its gratitude the city of Antwerp erected a fine monument to his memory.