Editing Inner German border (section)

===Protective strip===

On the other side of the signal fence lay the heavily guarded "protective strip" (''Schutzstreifen''), {{convert|500|to|1000|m|ft}} wide, which adjoined the border itself.<ref name="Rottman-23" /> It was monitored by guards stationed in concrete, steel and wooden watchtowers constructed at regular intervals along the entire length of the border. Nearly 700 such watchtowers had been built by 1989;<ref name="Rottman-29" /> the larger ones were equipped with a powerful 1,000-watt rotating searchlight (''Suchscheinwerfer'') and firing ports to enable the guards to open fire without having to go outside.<ref name="Rottman-28">[[#Rottman|Rottman (2008)]], p. 28.</ref> Their entrances were always positioned facing towards the East German side, so that observers in the West could not see guards going in or out. Around 1,000 two-man observation bunkers also stood along the length of the border.<ref name="Rottman-28" />

<div class="center">{{Gallery
|title=East German border watchtowers and bunkers
|width=180
|Ddr beobachtungsturm 11.jpg|The BT-11 (''Beobachtungsturm-11''), an 11 m (36 ft) high observation tower introduced in 1969. The top-heavy tower was unstable and vulnerable to collapsing.{{citation needed|date=March 2023}}
|Ddr beobachtungsturm 9.jpg|The BT-9 (''Beobachtungsturm-9''), a 9 m (30 ft)-high observation tower introduced in the mid-1970s as a more stable replacement for the BT-11{{citation needed|date=March 2023}}
|Fuerungsstelle Behrungen.jpg|A ''Führungsstelle'' or ''Kommandoturm'', a tower 6 m (20 ft) high that doubled as observation tower and command centre{{citation needed|date=March 2023}}
|Schießbunker PA hinten.JPG|An observation bunker, known as an ''Erdbunker'', preserved at [[Observation Post Alpha]], which accommodated one or two guards
|DDR steel watch tower cropped.jpg|A metal observation tower manned by three GDR guards. Some watchtowers were semi-portable and could be moved to new sectors when needed.{{citation needed|date=March 2023}}
}}</div>

Guard dogs were used to provide an additional deterrent to escapees. Dog runs (''Kettenlaufanlagen''), consisting of a suspended wire up to {{convert|100|m|ft}} long to which a large dog was chained, were installed on high-risk sectors of the border. The dogs were occasionally turned loose in temporary pens adjoining gates or damaged sections of the fence.<ref name="Rottman-25" />

[[File:Control strip hoetensleben.jpg|right|thumb|250px|alt=Strip of bare ploughed earth flanked by a concrete road on one side and a row of barricades and a fence on the other side, with buildings visible in the far background.|A preserved section of the border fortifications at Hötensleben. The patrol road is on the left; the primary control strip runs parallel in the middle; beyond it rise a row of ''[[Czech hedgehog]]'' barricades and the border wall.]]
The guards used an all-weather patrol road (''Kolonnenweg'', literally "column way") to patrol the border and travel rapidly to the scene of an attempted crossing. It consisted of two parallel lines of perforated concrete blocks which ran beside the border for around {{convert|900|km|mi}}.<ref name="Ritter-69">[[#Ritter|Ritter; Lapp (2007)]], p. 69.</ref>

Next to the ''Kolonnenweg'' was one of the control strips (''Kontrollstreifen''), a line of bare earth running parallel to the fences along almost the entire length of the border. There were two control strips, both located on the inward-facing sides of the fences. The secondary "K2" strip, {{convert|2|m|ft}} wide, ran alongside the signal fence, while the primary "K6" strip, {{convert|6|m|ft}} wide, ran along the inside of the fence or wall.<ref name="Rottman-17">[[#Rottman|Rottman (2008)]], p. 17.</ref> In places where the border was prone to escape attempts, the control strip was illuminated at night by high-intensity floodlights (''Beleuchtungsanlage''), which were also used at points where rivers and streams crossed the border.<ref name="Rottman-25" />

Anyone attempting to cross the control strips would leave footprints which were quickly detected by patrols. This enabled the guards to identify otherwise undetected escape attempts, recording how many individuals had crossed, where escape attempts were being made and at which times of day escapees were active. From this information, the guards were able to determine where and when patrols needed to be increased, where improved surveillance from watchtowers and bunkers was required, and which areas needed additional fortifications.<ref name="Rottman-17" />

Anti-vehicle barriers were installed on the other side of the primary control strip. In some locations, ''chevaux-de-frise'' barricades, known in German as ''Panzersperre'' or ''Stahligel'' ("steel hedgehogs"), were used to prevent vehicles being used to cross the border. Elsewhere, V-shaped anti-vehicle ditches known as ''Kraftfahrzeug-Sperrgraben'' (''KFZ-Sperrgraben'') were installed along {{convert|829|km|mi}} of the border and were absent only where natural obstacles such as streams, rivers, gullies or thick forests made such barriers unnecessary.<ref name="Rottman-23-24">[[#Rottman|Rottman (2008)]], pp. 23–24.</ref>