| Unit Name: | 12th Regiment of the Line 1831-1993 13th Regiment of the Line 1874-1947, 1976-1993 12th "Prince Leopold" - 13th Battalion of the Line 1993- |
| Dates: | 1831– |
| Country: |  Belgium |
| Branch: | Land Component |
| Type: | Infantry |
| Role: | motorized infantry |
| Size: | 650 soldiers |
| Command Structure: | Motorized Brigade |
| Garrison Label: | Spa, Belgium |
| Motto: | À l'avant-garde |
| Colors: | Red and Yellow |
| March: | Marche du 12e Régiment de Ligne Prince Léopold |
| Notable Commanders: | Alphonse Jacques de Dixmude |
The 12th of the Line (Prince Leopold) – 13th of the Line Battalion (French: Bataillon 12e de Ligne Prince Léopold - 13e de Ligne, Dutch; Flemish: Bataljon 12 Linie Prins Léopold - 13 Linie) is an infantry unit in the Land Component of the Belgian Armed Forces. It maintains the traditions of the 12th Regiment of the Line and 13th Regiment of the Line. 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]
The 12th Regiment of the Line is the oldest active Belgian infantry regiment. 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. It depicted the city's perron column.
The 13th of the Line was founded in 1874. It was disbanded in 1947, but in 1976 it reformed as an anti-tank regiment.
In 1993, the 12th of the Line and the 13th of the Line were merged to form the 12th Battalion of the Line "Prince Leopold" – 13th of the Line.
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.
The 12/13th Battalion of the Line comprises:
|-style="text-align: center; background: #F08080;"| align="center" colspan="20"|Lineage|-| width="20%" colspan="15" align="center"| 12th Regiment of the Line "Prince Leopold"| width="20%" colspan="5" rowspan="2" align="center" |12th-13th Battalion of the Line|-| width="20%" colspan="1" align="center"| | width="20%" colspan="14" align="center"|13th Regiment of the Line