The division was formed for the primary role of securing around of territory (the designated security zone) in north-eastern Bosnia within the NDH. The security zone encompassed the
Posavina,
Semberija and
Majevica regions between the Sava, Bosna, Drina and Spreča rivers. It roughly corresponded with the area of operations of the Partisan
3rd Corps. Himmler saw this task as critical to the safeguarding of important agricultural areas and settlements in the Syrmia region to the north. The division participated in what may have been the largest anti-Partisan sweep of World War II: Operation Maibaum. The 13th SS Division also participated in other divisional and
corps-sized anti-Partisan operations between March and May 1944.
Operation Wegweiser The division first saw action during (signpost) from 9 to 12 March 1944. Operation Wegweiser aimed to clear part of the Syrmia region which was occupied by Partisans who threatened the Zagreb-Belgrade railway. The Partisans were operating from forests around
Bosut and villages along the Sava. As the division entered the area, the Partisans withdrew to the southeast, avoiding a decisive engagement. Sauberzweig claimed the Partisans suffered 573 killed and 82 captured. Hoare writes that the division massacred hundreds of Serb civilians during the operation. According to
Vladimir Dedijer and
Antun Miletić, 223 civilians were killed in Bosut, 352 in
Sremska Rača, and 70 in
Jamena, mostly old men, women and children. The operation was a success in clearing the Bosut forests, but the Partisans returned to the area soon after it concluded.
Operation Save On 15 March 1944, Operation Save was launched to clear Partisans from the Semberija region. Sauberzweig wrote an open letter to the division: "We have now reached the Bosnian frontier and will (soon) begin the march into the homeland. ... The Führer has provided you with his best weapons. Not only do you (have these) in your hands, but above all you have an idea in your hearts – to liberate the homeland. ... Before long, each of you shall be standing in the place that you call home, as a soldier and a gentleman; standing firm as a defender of the idea of saving the culture of Europe – the idea of Adolf Hitler." Sauberzweig also ordered that each commander read a prepared message as his unit crossed the Sava River, which emphasised that the "liberation of Bosnia" and ultimately the liberation of "Muslim Albania" was their goal. This was a direct appeal to the Albanian troops as well as the Bosnians. The 27th Regiment crossed the Sava at dawn at
Bosanska Rača near the confluence with the
Drina. The rest crossed at
Brčko covered by an intense artillery bombardment. Contact was immediately made with Partisan forces, who quickly withdrew into the forests. The service support units remained north of the Sava in
Vinkovci, which became their permanent garrison area. The 27th Regiment advanced easily across the
Pannonian Plain through
Velino Selo to Brodac and then on to Bijeljina which was taken against light Partisan resistance late on 16 March. The 27th Regiment then consolidated its position in Bijeljina while the 28th Regiment and the divisional reconnaissance battalion () bore the brunt of the fighting as they advanced through
Pukis,
Čelić and Koraj at the foot of the Majevica mountains. Sauberzweig later recorded that the 2nd battalion of the 28th Regiment (II/28) "at Čelić stormed the Partisan defences with the (new) battalion commander
Hans Hanke at the point" and that enemy forces withdrew after a hard battle with heavy losses, low on ammunition. Once the area was secured, defensive positions were established along the Čelić–
Lopare road and company strength units were sent out to conduct reconnaissance. On the night of 17–18 March, elements of the Partisan
16th Vojvodina Division and
36th Vojvodina Division mounted unsuccessful attacks against the 28th Regiment's positions at Koraj and
Zabrđe, losing over 200.
Operation Osterei After Operation Save, the division remained relatively static for more than three weeks, mopping up and repelling local Partisan attacks. The Muslims were impatient to push further into Bosnia, but the reconnaissance battalion was heavily engaged on the divisional western flank, attacking positions held by the Partisan 3rd Vojvodina Brigade of the
36th Vojvodina Division at
Gornji Rahić on 26 March, killing 124 Partisans and capturing 14. The battalion captured several more Partisan positions in the following week. In early April, 200 Partisans of the
16th Muslim Brigade surrendered to the division. They were mostly former members of various Muslim militias who had been conscripted into the ranks of the Partisans. Operation Osterei (Easter Egg) began on 12 April 1944 intending to clear the Majevica mountain, which was held by elements of the 3rd Corps led by General
Kosta Nađ. The 27th Regiment quickly captured
Janja and drove through
Donja Trnova to reach the
Ugljevik coal mines, an important economic objective for the German war machine. Following fighting which continued into the evening of 13 April, the 27th Regiment reported Partisan casualties of 106 dead, 45 captured and two deserters along with large amounts of weapons and ammunition. The regiment also seized a huge amount of medical supplies from aid stations in the area of Donja Trnova. The 28th Regiment drove south through Mačkovac and during fighting around
Priboj, its 1st Battalion (I/28), made up of Albanians, incurred heavy casualties. The Partisan 3rd Corps then withdrew the 16th and 36th Vojvodina Divisions south across the Tuzla–
Zvornik road. The reconnaissance battalion continued the advance, driving into the western Majevicas and capturing
Srebrnik and
Gradačac then linking up with the Croatian Home Guard 1st Mountain Brigade. The Germans considered Operation Osterei a major success, achieving all objectives with minimal losses. During the final phase of Operation Osterei, I/28 was withdrawn from the fighting and transferred to
Pristina in Kosovo to form part of the
21st Waffen Mountain Division of the SS Skanderbeg (1st Albanian) being raised by Himmler's order. A new I/28 was raised from other divisional units and recruits. In the latter part of Operation Osterei, , lightly armed and mobile "hunter teams" of company or battalion strength, were used to break up and harass Partisans still operating on the flanks. These teams killed over 380 Partisans and captured over 200 between 21 and 23 April. By mid-April, half of the security zone had been cleared of Partisans.
Operation Maibaum The ambitious goal of Operation Maibaum (Maypole) was to destroy the Partisan 3rd Corps.
Army Group F ordered
V SS Mountain Corps to form a blockade along the Drina to prevent the Partisan force from crossing into Serbia. Operation Maibaum was one of the largest counter-insurgency operations of World War II and included 7th SS Division and NDH forces. The 13th SS Division was under the command of V SS Corps, and the primary tasks of the division were to capture Tuzla and Zvornik, then drive south parallel with the Drina to meet other Corps elements. The original plan included the parachute insertion of the
500th SS Parachute Battalion into the
Vlasenica area, but this was cancelled due to unsuitable weather. Flank security was to be provided by the reconnaissance battalion in the Srebrnik area. The deployment south of the Spreča, and therefore outside the security zone, during Operation Maibaum was ordered by the corps commander, Phleps, despite opposition from Sauberzweig. This caused friction between the two that eventually required Himmler's intervention. On 23 April, the 28th Regiment pushed south along mountain roads through Tuzla. The following day it continued as far as
Stupari. On 25 April, the 27th Regiment advanced south to capture Zvornik. At the same time, the 28th Regiment sent I/28 east towards Vlasenica and II/28 continuing south towards
Kladanj, capturing the town on 27 April. Due to the level of the
Drinjača at Kladanj, instead of fording the river and pushing east towards Vlasenica, II/28 continued south-east towards
Han Pijesak, where they met elements of 7th SS Division advancing north. I/28 captured Vlasenica on 28 April but was almost immediately attacked from the east by two Partisan divisions. A third Partisan division surrounded the headquarters of the 28th Regiment at
Šekovići, 30 kilometres north-west of Vlasenica. Both II/28 and the reconnaissance battalion were rushed to Vlasenica, where II/28 relieved the battered I/28 and then surrounded Šekovići. After a 48-hour battle, during which II/28 was decimated, the town was taken. While the battle of Šekovići raged, the 27th Regiment extended the Drina blockade further south, ambushing a Partisan column and reaching
Nova Kasaba on 30 April. After the situation at Šekovići improved on 1 May, the 27th Regiment returned to patrolling the Tuzla–Zvornik road. The 28th Regiment moved to the Simin Han-Lopare area on 5 May, while the 7th SS Division pursued the Partisans withdrawing south. Operation Maibaum had not only stopped the Partisan 3rd Corps from crossing the Drina into Serbia, it had scattered the Partisan formation. On 6 May, V SS Mountain Corps ordered the division to return to the security zone north of the Spreča.
Operation Maiglöckchen On 17–18 May 1944, the division, along with the local Majevica-Tuzla Chetnik unit commanded by
Radivoje Kerović, commenced Operation Maiglöckchen (May Bell) to destroy several Partisan brigades in the Majevicas. The Partisans were encircled in the Stolice heights. An attempt by the Partisan 16th Vojvodina Division to relieve the surrounded force was defeated by the reconnaissance battalion and elements of the 28th Regiment. The relieving column was driven back across the Spreća. After heavy bombardment by the artillery regiment, the trapped Partisan force escaped south out of the pocket under cover of darkness on 18 May. The Partisans suffered considerable casualties, for example, the 17th Majevica Brigade of the
27th East Bosnia Division lost 16 killed and 60 missing. At the conclusion of Operation Maiglöckchen, the 27th Regiment remained near Zvornik and the 28th Regiment deployed near
Srebrenik. == Cooperation with local forces ==