He is known for taking part in the Battle of Petsamo against the Red Army and Soviet forces.

He served in the Lapland border guard from 1933 until the start of the winter war and at the same time also served as the commander of the Rovaniemi garrison from 1935 to 1938 and from the beginning of 1939 as a company commander.

Pennanen started fighting in the Winter War as the commander of Er.P 16 and from the beginning of December until the armistice as the commander of Osasto Pennanen in the Petsamo front and area in the Battle of Petsamo.

He served as commander of the Lapland border guard again from 1 July 1947 to 1 March 1956.

At the same time, he served as deputy head of the Border Guards from 1 September 1947 to 4 May 1949.