The majority of the successful SOE operations in Europe took place in countries occupied by the Germans after the outbreak of war in 1939, Hitler's forces being regarded as foreign invaders. In Czechoslovakia it was different. The country, which had large numbers of ethnic Germans living within its borders, had been occupied since 1938, allowing the Germans to establish a strong hold on the country which limited the opportunities for subversive action by resistance movements. Nevertheless, resist the Czechs did, despite the Germans conducting savage and indiscriminate reprisals. It was against this background that SOE attempted to infiltrate its agents into Czechoslovakia in 1941, their role being to help in co-ordinating and expanding the resistance movement and to establish communications with the Czech authorities in the UK. Successful actions were admittedly few before 1942 when one of the most successful SOE-backed operations resulted in the assassination of Reinhard Heydrich, the highest-ranking Nazi to be killed by any resistance group. The huge wave of reprisals against the civilian population which followed severely hampered SOE activities in the immediate aftermath. Another factor which limited SOE's ability to infiltrate Czechoslovakia and to supply the resistance was the distance and difficulty experienced by the RAF in flying to the region. During the short nights of summer, no flights could be attempted. This changed in September 1943 when sorties were able to be conducted from Italy, and by 1944 the scale of operations increased both in frequency and scale. More than 300 Czechs were trained by SOE and, in conjunction with local resistance groups, those that managed to infiltrate back into their homeland, kept the occupying forces constantly on the alert, ensuring that Germany's eastern flank was never entirely secure. This is the first full, official account of SOE in Czechoslovakia, compiled by SOE headquarters staff who had direct access to all the organisation's records, many of which were destroyed after the war.