The 12th of the Line (Prince Leopold) – 13th of the Line Battalion (French: Bataillon 12e de Ligne Prince Léopold - 13e de Ligne, Dutch: Bataljon 12 Linie Prins Léopold - 13 Linie) is an infantry unit in the Land Component of the Belgian Armed Forces.

From 2011 until 1 January 2017 the regiment was a part of the Light Brigade and on that date the regiment joined the Motorized Brigade.

[1] It was created on 31 March 1831, and since 1984 has been authorised to bear the title "Prince Leopold" which was originally bestowed on it in 1915, during the First World War.

The badge of the 12th Regiment of the Line was based on the coat of arms of the city of Liège where the regiment had its barracks.

The standards of the unit carry the following citations: For the 12th Regiment of Line: For the 13th Regiment of Line: As well as a fourragère of the Order of Leopold.