He taught for 20 years, then went on a voyage into Arctic seas and conceived the idea of an expedition to the North Pole. He thought that in summer the effect of the constant sunshine (insolation) would be to melt the ice and allow passage to the Pole. The plans had been made, about half the funding had been subscribed, and a ship had been purchased when the project was disrupted by the Franco-Prussian War in 1870. Lambert enlisted in the National Guard and died of wounds at the Battle of Buzenval (1871).