Blinkerdenkmal, War memorial on Landgrafen Mountain in Jena, Germany

Blinkerdenkmal is a roughly four-metre-high memorial on the Landgrafenberg in Jena: a cube of limestone that once carried an oversized steel helmet and, on front and back, a large Iron Cross with oak leaves. After 1945 the helmet, cross, oak leaves and inscription were removed; in 2021 a stylised steel helmet with a signal lamp (based on the L Blink 17 aircraft signalling device) and the inscription "1914 DEN GEFALLENEN 1918" were added.

The memorial was inaugurated in 1921 to honor German signal troops who died in World War I. After 1945, military symbols were removed to reflect changing times.

The site honors soldiers who communicated using light signals, a method that was revolutionary before modern radio technology existed. Visitors can still read inscriptions today that remember these pioneers of military communications.

The memorial stands on the Landgrafenberg, near the 363-metre, bare Windknollen hill where the signal troops once trained; the site is reached on foot through the woods, and the reservist association that restored it also tends the two Serbian spruces it donated and the surrounding ground.

In May 2018 the Reservistenkameradschaft asked Jena's culture committee to return the memorial to its 1921 form, prompting public debate about symbolic remilitarisation. The result was a new inscription, "1914 DEN GEFALLENEN 1918", and a stylised steel helmet topped with a signal lamp modelled on the L Blink 17 aircraft signalling device, inaugurated on 29 May 2021, exactly 100 years after the first ceremony.