The 'Čazma Operajica' was a Yugoslav attack by the partisan forces of Marshal Josip Broz Tito on Čazma in the puppet state of Croatia within German-occupied Yugoslavia (28 November/1 December 1943).

The operation stands as classic example of guerrilla attack on a defended stronghold, and is typical of the many such efforts, both successful and unsuccessful, throughout the Axis occupation of Yugoslavia. The key element of the operation and all its brethren was the need for a force larger than that actually attacking the objective to shield the offensive force from attempted interventions by the enemy’s relief forces. Allied with this was the requirement for the investment to succeed rapidly and thereby deny the larger and better equipped relieving forces the time to make their superiority tell.

The location of Čazma in the Moslavina region near the Yugoslav partisan stronghold of the Moslavačka mountain area made its retention by the Germans and Croats a major threat to the partisan-held area. The partisans' first successful attack was carried out on 14 October 1942, when the 'Moslavina' Partisan Detachment undertook a short engagement in which it suffered no losses but killed two and wounded one Axis soldier, and also managed to capture 18 gendarmes and 50 Ustase soldiers of the local 'preparatory' (field replacement) battalion, all of whom were then released to spread propaganda and demoralise other Croat units. The partisans left the town on the following day and fell back to their mountain retreat with all the equipment they had seized.

A second attack was made on 2/3 September 1943, again by the 'Moslavina' Partisan Detachment, after the strength of Čazma’s defences had been increased and the garrison enlarged. The attack had limited objective of checking the German part of the garrison until the garrison’s Croat element had become demoralised and could therefore be captured and disarmed. On this occasion the partisans suffered one man killed and seven wounded, while the Croat losses were only two men wounded but six officers, four NCOs and 150 soldiers taken prisoner and all the Croat weapons were seized. About 12 captured Croats joined the partisans, and the others were released to spread the news of the partisan success and thereby further demoralise the Croat forces.

This attack resulted in a further strengthening of Čazma’s defences, including the erection of barbed wire entanglements and the laying of land mines, by Pukovnik Stjepan Peričić's 1^st Mountain Brigade, as well as the creation of a plan for the rapid movement of reinforcements into the area from Bjelovar and even Zagreb in the event of another attack.

In November 1943 the partisans established a large liberated area in the Moslavina, Kalnik and Bilo mountain areas, but the Axis retention of Čazma, controlling communications between Zagreb, Ivanić Grad and Bjelovar, prevented the consolidation of the three partisan areas into a single entity. Then the arrival of the 28^th 'Slavonia' Assault Division, which was returning to Slavonia from operations in north-western Croatia, offered the Staff of the 2^nd Operational Zone the opportunity to plan and attack to take and hold Čazma. In the forthcoming operation, the Axis forces had the Čazma garrison of some 500 men of the 1/5^th Mountain Regiment of the 1^st Mountain Brigade, 220 German field police of Generalleutnant Josef Brauner von Haydringen’s 187^th Reserve-Division, 60 to 70 gendarmes, 20 Ustase soldiers, and 30 to 40 miscellaneous others; available for any relief effort was Podpukovnik Brkić's 5^th Mountain Regiment from Ivanić Grad.

The partisan force comprised Nikola Kličković's 1^st 'Moslavina' Brigade to attack Čazma, Stevo Čučković's 'Moslavina' Partisan Detachment with one battalion supporting the attack on Čazma and the others guarding the approaches from Popovača and Ludina, the 28^th 'Slavonia' Division to prevent relief attempts with Nikola Demonja’s 17^th 'Slavonia' Brigade in the area of Graberja and Palačana to hold the approaches from Zagreb and Ivanić Grad, and the 21^st 'Slavonia' Brigade in the area of Stefanje to hold the approaches from Bjelovar, and the 'Zagreb' Partisan Detachment holding the approaches from Vrbovec and Dubrava.

The partisan attack began at 03.00 on 28 November, but did not take the defence by tactical surprise as such an attack had been expected for some time and measures were in hand to hold the town until the relief force arrived and drove off the partisans. However, the partisans gained a measure of tactical surprise when they continued their attack by day despite air attacks. One battalion of the 'Moslavina' Partisan Detachment managed to split the defence and thus divide the Germans and Croats into separate pockets. The fighting continued for the entire day and the following night, and by the morning of 29 November the resistance of the 1/5^th Mountain Regiment had been broken, leaving only the Germans in the fortified municipal building. At 10.30 the German commander decided to attempt a breakout toward the Česma river where, pursued by the partisans, many of the Germans drowned as they attempted to swim across. At about 11.00, after 31 hours of fighting, the battle for Čazma was over. The relief attempt by the 5^th Mountain Regiment was ambushed by the 17^th 'Slavonia' Brigade on the first day, and there followed German elements and parts of Poglavnik Bodyguard Brigade. On 29 November the 1^st Mountain Brigade attempted and failed to advance from Kriz and Dabci, and then another effort was made from Ludina, Kompator and Mustafina Klada with the support of by artillery, armoured vehicles and six aircraft.

A counterattack by the 17^th 'Slavonia' Brigade took this second effort in flank and forced it to withdraw, and also shot down two Henschel Hs 126 tactical reconnaissance aircraft.

On 30 November, a German column of some 500 to 600 men tried to break through the 17^th 'Slavonia' Brigade and reach Čazma, but this too was taken kin flank and compelled to pull back. Appreciating that to its front there was a strong garrison on Bjelovar, the 21^st 'Slavonia' Brigade decided to send its 1^st Battalion, together with a mortar section, to make a feint attack on village of Narta once the Axis column had passed it, while the 2^nd and 4^th Battalions took ambush positions and the 3^rd Battalion remained in reserve.

By the evening seven Croat soldiers had been killed and 16 wounded, while the Germans suffered heavier losses. The partisan losses included the commander of the 1^st Battalion, Jakov Bosiočić Veseli. Once regrouped, the Croat and German troops divided into three columns on 29 November and tried to outflank the positions of the 21^st 'Slavonia' Brigade, hose staff was forced to commit two reserve companies to reinforce the defence. After the fall of night, a partisan counterattack forced the relief columns to fall back to Narta. Fog caused considerable confusion as many of the partisans were wearing items of German uniform recently captured in Koprivnica, and this made it difficult to distinguish between friend and foe. The Axis forces launched a new attack on 30 November from Narta via Hills 140, 168 and 137 and the village of Laminac. Falling on the partisans' flank and rear, this succeeded in capturing parts of the brigade supply column, but then a partisan counterattack restored the position. In order to exploit this partial success, the German and Croat force began a new attack, driving back the partisan 2^nd and 4^th Battalions and capturing the village of Stefanje, where it halted for the night. During night patrol of the 1^st Battalion was ambushed by the Germans and destroyed.

The 21^st 'Slavonia' Brigade planned to attack the village of Stefanje at 17.15 on 1 December, but before this could be undertaken the Germans decided to call off their operation toward Čazma and started to pull back at 15.00.

The battle for the town of Čazma cost the partisans 63 casualties (15 killed and 48 wounded), and the partisans claimed to have inflicted losses of 270 killed, 80 wounded and 240 taken prisoner, while another 150 Axis troops were missing, mostly drowned. The partisans also captured two 37-mm anti-tank guns, two 81-mm (3.2-in) mortars, 60-mm (2.36-in) mortars, six general-purpose machine guns, 24 light machine guns, 30 sub-machine guns, 500 rifles, one staff car and 60 horses; another 50 rifles, two general-purpose machine guns, six light machine guns, and several sub-machine guns and pistols were recovered 10 days later from Česma river when the water level fell. The 17^th 'Slavonia' Brigade claimed to have killed 300 Axis soldiers and captured 40 others, destroyed 17 trucks and two Hs 126 aircraft, and seized a weapons haul including two 75-mm (2.95-in) mountain guns with 150 rounds, two 37-mm anti-tank guns with 170 rounds, two light mortars, seven heavy machine guns, seven light machine guns, six sub-machine guns, 100 rifles, eight artillery ammunition limbers, and 200 hand grenades.

For their capture of the partisan headquarters in Laminac the Croats admitted the loss of eight killed, 18 wounded and 7 missing, and the Germans lost four killed, 20 wounded and three missing. The German report for the fighting in the Bjelovar sector lists 12 killed and 37 wounded Germans, nine killed, 13 wounded and 10 missing Croats, and claimed 75 partisan losses. The 21^st 'Slavonia' Brigade reported 22 killed and 64 wounded, of whom five later died, and claimed 80 Axis soldiers killed or wounded, and the capture of one light mortar, two staff cars, three light machine guns, two sub-machine guns and 26 rifles. In total, the partisans claimed around 600 killed or wounded for entire operation while capturing 300 soldiers (including 11 officers), of which 110 joined the partisan movement. Čazma then remained in partisan hands until March 1945, when it was lost for few days.