Shortly before the 1939 Invasion of Poland he was assigned to the 110th reserve Cavalry Regiment as a deputy commander. His unit was to enter combat as a second-line formation, but fast advances of the Wehrmacht made the completion of training impossible. On 11 September it was moved to Wołkowysk, from where it marched towards Grodno and Augustów Forest. It fought several skirmishes against the German army and took part in the defense of the city against the Red Army. After two days of heavy fighting against the numerically superior Soviets, on 20 September Grodno was lost and three days later gen. bryg. Wacław Przeździecki, the commander of the defense of the Grodno area, ordered all his troops to escape to neutral Lithuania. The 110th Regiment was the only unit to disobey this order. The unit joined with the remnants of several routed regiments and fought its way towards the capital Warsaw. The unit got surrounded by the Red Army in the Biebrza river area and suffered serious casualties, but managed to break through the enemy defenses. After that, Lieutenant ColonelJerzy Dąbrowski, the commander of the regiment, decided his unit should disband. A group of approximately 180 men wanted to continue, and Dobrzański took command of them and led them towards Warsaw, which was under siege. Warsaw capitulated on 27 September, before Dobrzański and his men were able to reach it. That left him faced with three choices: disband, evacuate to France, or continue the fight. Approximately 50 men volunteered to continue the fight. He led his unit southwards to try to break reach France. On 1 October 1939 they crossed the Vistula near Dęblin and started their march towards the Holy Cross Mountains. The same day his unit fought their first skirmish against the Germans. After that he decided to stay in the Kielce area with his unit and wait until the Allied relief came, which he expected in the Spring of 1940. He also swore that he would not take off his uniform until after the war. He named his force the "Separated Unit of the Polish Army". On 6 October the Battle of Kock ended the resistance of the last major unit of the Polish Army. With the support of the local civilian population, Hubal and his men managed to evade the Germans. In March 1940 his unit inflicted heavy casualties on a number of German units in ambushes. The German authorities responded with reprisals against the civil population, burning several villages and killing an estimated 700 civilians. Due to these reprisals local sentiment turned against Hubal's unit, and the newly formed ZWZ became concerned that this would inhibit their ability to recruit. The ZWZ and the Government Delegate's Office at Home ordered Hubal to disband his unit. He refused to do so.
Death and legacy
On 30 April 1940 his staff quarters, in a ravine near the village of Anielin, were ambushed. In an unequal battle Dobrzański and most of his men were killed. The Germans desecrated his body and put it on public view in the local villages. They then transported it to Tomaszów Mazowiecki and either burnt it or buried it in an unknown location. The remnants of the "Separated Unit of the Polish Army" continued the struggle until 25 June 1940, when it was disbanded. In 1949 Dobrzański's son, Ludwik, emigrated to England and became a property developer. He died on 15 December 1990 in Bedford. In 1966 Henryk Dobrzański was posthumously awarded the Golden Cross of the Virtuti Militari and promoted to Colonel. Currently almost 200 organisations and institutions bear his name, including 82 Scouting groups, 31 schools and several military units. There are streets named after him in almost every Polish city. The site of his burial remains unknown. In 1973 the film Hubal, based on his resistance campaign, was released. The pseudonym "Hubal" comes from his family coat of arms.
