 Complete the following phrase:  As the threat of war became apparent and the production rate of Polish 7TP tank was insufficient, it was decided to buy vehicles abroad. Poles were most interested in French SOMUA S35 tanks, but the proposal was refused by the French government. In 1938 the Polish Army bought one according to other sources, two or three R35 tank for testing. After a series of tests it was found that the design was disappointing: the engine was overheating, the suspension was tough, and armament insufficient. In April 1939 it was finally decided to buy a hundred R35 tanks as an emergency measure. The first shipment of fifty other sources lower the number to 49 arrived in Poland in July 1939, along with three Hotchkiss H35 tanks bought for testing. In August they were mostly put into service with the Łuck-based 12th Armoured Battalion. At the beginning of the Invasion of Poland 45 or 46 tanks formed the core of the newly created 21st Light Tank Battalion that was part of the general reserve of the Commander in Chief. The unit was to defend the Romanian Bridgehead, but was divided after the Soviet invasion of Poland of 17 September. Late September the unit was withdrawn to defend the Romanian Bridgehead. Subsequently, 34 tanks were withdrawn to Romania. Six tanks were attached to the 10th Motorized Cavalry Brigade in Stanisławów today Ivano-Frankivsk; they forced their way through Kolomyia and three vehicles crossed the Hungarian border. The remaining tanks - four R35s and three H35s - were put into service with the improvised Dubno Operational Group and took part in the battles of Krasne on 19 September with the 