The object of this thesis is to ascertain what was the most significant factor in determining support for Gaullism in unoccupied France. The first aim of this dissertation is to study the ways in which the Mers-el-Kebir incident affected de Gaulle's movement. The second aim is to examine the influence of other aspects on Gaullism, such as the origins and organisation of the Free French movement, the propaganda and policies of the Vichy regime, the opinions of the French Resistance, and other external influences such as American, British and Russian foreign policy. This thesis will try to offer some conclusions as to if, why and when de Gaulle and the Free French movement became popular in France. It will also compare the reasons for his popularity and unpopularity and rate them against the effect of the Mers-el-Kebir incident as well as determining whether the extent of his support was beyond his control or was due to his own actions.