'The 'Reinhard-Linie' was a German defence line on the western side of south central Italy, running to the north-east from its link with the 'Gustav-Linie' defences at Sant' Ambrogio (on the junction of the Liri and Rapido rivers to form the Garigliano river) via Monte Cesima to Castel di Sangro back on the 'Gustav-Linie' in the Apennine mountain range (autumn 1943).
Otherwise known as the 'Bernhardt-Linie', the 'Reinhard-Linie' formed the outer defence of the 'Gustav-Linie', and was itself protected by the 'Barbara-Linie' between the lower reaches of the Volturno river and the Garigliano river: these defences were collectively known to the Allies as the 'Winter Line'.
Constructed in the autumn of 1943 at the instigation of General Hans-Valentin Hube, commanding the XIV Panzerkorps in Generaloberst Heinrich-Gottfried von Vietinghoff-Scheel’s 10th Army, the 'Reinhard-Linie' was based on the natural defence provided by the Mignano defile, and though intended (like the 'Barbara-Linie') as a tactical delaying position in front of the main 'Gustav-Linie', it was in many ways superior as a strategic block to the entrance of the Liri river valley and the approaches to Rome.
Hube appreciated that the 'Reinhard-Linie' was too far forward from the 'Gustav-Linie' for an ideally co-ordinated defence, but with his corps engineers he nonetheless constructed well-sited positions that made full use of the terrain’s features to provide deep rather than linear defences.
The Allies broke through this line in 'Raincoat'.