the strikes continued in 2015 with a three-day railway strike starting on 21 april 2015, the gdl's seventh strike in 10 months. this was followed by a strike from 4–10 may, the longest strike in deutsche bahn's history. a further strike started on 19 may 2015 and finished on 21 may as the gdl and deutsche bahn agreed to allow arbitration to resolve the conflict.