In spring 1912 there were major problems in the association Ung Dansk Kunst resulting from disagreements as to whether to take part in the Berlin Secession exhibition, to which not all members of Ung Dansk Kunst had been invited. Meanwhile, Giersing, Sigurd Swane and Knud Kyhn insisted on exhibiting. The Danes enjoyed no success; there would have been more interest in seeing Matisse than Giersing, wrote one German reviewer. The most important result of this international venture was the dissolution of Ung Dansk Kunst, something over which Giersing did not mourn.
In 1913 Giersing was again a guest exhibitor in Den frie Udstilling, where, among other things, he showed the large-scale football picture from 1911. In September he took part in a group exhibition of "Works by Six Young Danish Painters" in the Copenhagen Art Association, where the reviewers in general complained of not being able to find pictures which they could recognise as finished works. They were all thoroughly lambasted, and Giersing sold nothing. But in one respect this exhibition was important. It helped to strengthen the feeling of solidarity among four painters who had stood shoulder to shoulder in the difficult battles in Ung Dansk Kunst. They were soon to participate in the formation of the association called Grønningen. But before Giersing could help to bring about the dissolution of Den frie Udstilling, he had to get in as a member.
Artistic animosity was only part of the explanation of the continuing opposition to him of most members of Den frie Udstilling. There was doubtless also the fear that from an organisational point of view he might turn out to be a dangerous element in the association, where characteristically one of the sources of disagreement was on the very question of admitting new young members. In 1914, however, Giersing finally became a member, and the following year, partly as a result of the refusal to admit some young artists, he helped break up the association and form a new one, which soon adopted the name of "Grønningen".
Although Giersing quickly came to play a quite central role in Grønningen, there is nothing to suggest that he was particularly active in the break-up as such of Den frie Udstilling. In Grønningen, however, he was very active indeed, and after the first power struggle there in 1915 he was able from 1916 to occupy an unchallenged position as leader in the association.