Rommel’s asparagus (Rommelspargel in German) were 4-to-5-meter-long (13 to 16 feet) logs which the German defenders placed roughly vertically in the fields and meadows of Normandy to cause damage to Allied gliders and paratroopers expected to be used in the invasion of Northern France. Optimally, wire would be strung between them (as in the sketch below), and mines often attached that would detonate on impact.
Rommelspargel took their name from Field Marshal Erwin Rommel, who – as “General Inspector of the Western Defences” charged by Hitler with strengthening the fabled “Atlantic Wall” – ordered their design and usage. Rommel himself called the defensive concept Luftlandehindernis (“air-landing obstacle”).