The light and medium batteries.

 There was a number of different guns present at the defence line. From 7,7 cm field guns
 to 15 cm field haubits and naval guns.
 Guns that came from the army artillery guns from the navy and coastal defence. Gunners form the
 army and gunners from the navy.

 It is possible that occupied guns had been used. The Defence Line was reserve, and therefore it didn't
 get the modern guns. They  were sendt to the Western  and the Eastern Fronts.
 
 We know for sure, that in one occation occupied guns has been used (Beutekanonen). At at least one
 battery Frensh guns from Schneider-Canet has been used. Beside France, only Denmark had guns like
 these, and the Danish guns were at the time placed outside Copenhagen. 
  
 On several occations we meet guns that has been taken out of the old Kiel Forts as Herwarth,
 Röepsdorff, Höhe and Freienfelde.
 Forts from the late 19th century and from an artillery point of view, old and useless.

Clip: Firing the 7,7 cm field gun

 In general there was great need for artillery. The number of men in the Imperial Army was doubled 6
 times, which meant bid changes in the organisation. From 669 to 2300 infantry battallions and from 642
 to 2900 field artillery batallions.
 Initially the Army-Corps (two infantry divisions and a artillery brigade) were the biggest unit. Later the
 division became biggest unit (one infantry brigade, an artilley command of a size fit ro the task and a
 heavy artillery batallion.)
 In order to arm all the new artilley units, the batteries went from 6 to 4 guns. Also occupied guns were
 used.
 It is most lightly, that occupied guns has been used in the Defence Line in Jutland which after all was
 secondary. 
 
 It seems, that new artillery units were formed when guns for them were available.