On 10 February 1920 the plebiscite was held in
Zone I, the later
Northern Schleswig, where 74.9% (75,431 votes) voted to become Danish, while 25.1% (25,329 votes) voted to stay German. In three of the four major towns, especially in the southern region directly at the border with Zone II, German majorities existed, with a German majority as large as 70 to 80 percent in and around
Tønder (plus southerly
Udbjerg) and
Højer. It was mostly this area that caused controversy after the voting, especially as these towns had been included north of Clausen's first line. Although Clausen correctly estimated Tønder to be vastly pro-German, he considered the town to be economically dependent on its pro-Danish rural uplands, and placed both the town and its uplands north of his first line. Local majorities for Germany also existed elsewhere: In the small town of
Tinglev, in the city of
Sønderborg, site of a substantial German navy base, and the city of
Aabenraa. Like Tønder and Højer, Tinglev directly bordered Zone II. Both the latter cities, however, lay "isolated" in pro-Danish surroundings. The vote in Central Schleswig (
Zone II) took place on 14 March 1920, where 80.2% (51,742 votes) voted to stay German, while 19.8% (12,800) voted to become Danish. Since a Danish majority in this zone was produced in only three small villages on the island of
Föhr, none of which were near the coming border, the
Commission Internationale de Surveillance du Plébiscite au Slesvig decided on a line almost identical to the border between the two zones. The poor result for Denmark in Central Schleswig, particularly in
Flensburg, Schleswig's largest city, triggered Denmark's 1920
Easter Crisis. A plebiscite was not held in the southernmost third of the province (
Zone III which included the region south of Zone II until the
Schlei,
Danevirke, and the city of
Schleswig) as the population was almost exclusively pro-German. The Allied Powers had offered to include this region in the plebiscite, but the Danish government had expressly asked for Zone III to be excluded. The small part of the historical province located south of Zone III was not included in plebiscite plans among the Allied Powers, and the same applied in Denmark, since the extreme south of the former duchy was considered to be a completely pro-German area. Selected results in detail: . == Settlement of the Danish-German border ==