Operation Otkos 10 was a military offensive undertaken by the Croatian army against the Yugoslav People's Army

Yugoslav People's Army

The Yugoslav People's Army , also referred to as the Yugoslav National Army , was the military of the Socialist Federal Republic of Yugoslavia.-Origins:The origins of the JNA can...

 (JNA) in SAO Western Slavonia

SAO Western Slavonia

SAO Western Slavonia or Serbian Autonomous Oblast of Western Slavonia was a Serbian self-proclaimed autonomous region within Croatia. It was formed on 12 August 1991 and was subsequently included into Republic of Serbian Krajina...

. The operation lasted from October 31, 1991, until November 4, 1991 and ended with a victory for Croatia.

JNA offensive up to October

After the attacking forces of the 5th JNA corps (Banja Luka corps) had successfully crossed Sava river into Croatia

Croatia

Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...

 and captured Okučani

Okucani

Okučani is a village in western Slavonia, Croatia. It is located at the contact point between the Posavina plain and the southern slopes of Psunj; 19 km southeast of Novska and 17 km west of Nova Gradiška; elevation 119 m. Chief occupations are farming, livestock breeding, fishing and...

 in western Slavonia, it was their primary objective to advance along the Pakrac

Pakrac

Pakrac is a town in western Slavonia, Croatia, population 4,852, total municipality population 8,482 . Pakrac is located on the road and railroad connecting the regions of Posavina and Podravina.-Name:...

 - Grubišno Polje

Grubišno Polje

-Demographics:In the 2001 census, the municipality had 7,523 inhabitants, with the following ethnic makeup:* 4,692 Croats* 1,356 Czechs* 872 Serbs* 228 Hungarians...

 route and link up with the 28th Partisan Division near Bilogora

Bilogora

Bilogora is a low mountainous range in central Croatia. It consists of a series of hills and small plains some 80 kilometres in length stretching in the direction northwest-southeast, along the southwest part of the Podravina region...

, sever the Podravska magistrala trunk road and reach the Hungarian border, thus completely severing Slavonia from the remainder of Croatia, including the capital - Zagreb

Zagreb

Zagreb is the capital and the largest city of the Republic of Croatia. It is in the northwest of the country, along the Sava river, at the southern slopes of the Medvednica mountain. Zagreb lies at an elevation of approximately above sea level. According to the last official census, Zagreb's city...

.

Aiding the JNA offensive was the local Serb population in SAO Western Slavonia which had taken up arms in early 1991.

The mountainous regions provided a base for the Serb forces, which thence proceeded to fire grenades at nearby cities and villages in the lowlands.

Croatian counteroffensive

In order to prevent JNA's attempt to cut off Slavonia, and to stop the expulsions from western Slavonia, the Croatian troops undertook their first offensive operation of this scale during the homeland war.

The military aim of Otkos 10 was to secure the Bilogora hills and to capture favourable positions for further advance towards Papuk

Papuk

Papuk is the largest mountain in the Slavonia region in eastern Croatia, near the city of Požega. It extends between Bilogora to the northwest, Krndija to the east, and Ravna gora and Psunj to the southwest....

 mountains to the southeast thus securing land communication between Slavonia and the rest of Croatia.

Croatian troops involved included: 151st brigade (Samobor

Samobor

Samobor is a town in the Zagreb County, Croatia. It is part of the Zagreb metropolitan area.-Geography:Samobor is located west of Zagreb, between the eastern slopes of the Samoborsko gorje , in the Sava River valley.-Population:...

), 127th brigade (Virovitica

Virovitica

Virovitica is a Croatian town near the Croatian-Hungarian border. It is situated near the Drava river and belongs to the historic region of Slavonia. Virovitica has a population of 14,663, with 21,327 people in the municipality...

), 57th battalion and National defense detachment (Grubišno Polje), 24th mixed artillery battalion, 52nd battalion (Daruvar

Daruvar

Daruvar is a town in central Croatia, population 9,815 , total municipality population 13,243 ....

), a T-55

T-55

The T-54 and T-55 tanks were a series of main battle tanks designed in the Soviet Union. The first T-54 prototype appeared in March 1945, just before the end of the Second World War. The T-54 entered full production in 1947 and became the main tank for armored units of the Soviet Army, armies of...

 tank platoon of 105th brigade (Bjelovar

Bjelovar

Bjelovar is a city in central Croatia. It is the administrative centre of Bjelovar-Bilogora County. During the 2001 census, there were 41,869 inhabitants, 90.51% which are Croats....

), 19th mixed antitank artillery battalion (Virovitica), special police forces from Bjelovar, and a Križevci volunteer company.

End of the operation

The operation was successfully concluded by November and Croatia captured 21 villages and approximately 270 square kilometers of its territory, thwarting JNA's strategic plan to isolate Slavonia.

More importantly, a strategic supply route via Virovitica - Grubišno Polje - Kutina

Kutina

Kutina is a small city in central Croatia, the largest settlement in the hilly region of Moslavina, in the Sisak-Moslavina county. The town proper has a population of 14,814 , while the total municipality population is 22,815....

 road was reopened, which was the most important land route to Slavonia until Operation Flash

Operation Flash

The Serbs in western Slavonia took part in the organized rebellion against the government of the Republic of Croatia that had just proclaimed independence in June 1991, by proclaiming the Serbian Autonomous Oblast of Western Slavonia in August 1991...

. Furthermore, this operation set the stage for the Operation Orkan 91

Operation Orkan 91

Operation Orkan 91 was a military operation during the Croatian War of Independence. After successful completion of Operation Otkos 10, the first offensive operation of such scale by Croatian army in the homeland war, Croatian troops were in position to retake further territory and neutralize a...

which marked yet another advance by Croatian army in this area.