Late on the evening of 14 May, after the vain first attempt, the Germans drew up a plan for an assault on the Bath Line on the following day. They believed that the defenders would offer little resistance and therefore decided to rely on intimidation and deception.
The assault plan was devised personally by the commander of XXVI Army Corps, General Wodrig, and the commander of the SS Verfügungsdivision, SS Gruppenführer Hausser, together with their staffs. From their headquarters at Ginneken, south of Breda and some distance from the actual front, they decided to send a negotiator ahead of the attack.
A message was drafted demanding the immediate and unconditional surrender of the Bath Line. Should the defenders refuse, the Germans threatened to unleash a devastating bombardment involving no fewer than twenty-one artillery battalions, six squadrons of Ju 87 Stukas, and five squadrons of medium bombers.
The authors of this ultimatum displayed a remarkable degree of imagination. In reality, the Germans had no more than a single artillery battalion, two squadrons of Stukas on call, and perhaps two to three squadrons of medium bombers available for the operation, also on call. Indeed, neither the 18th Army nor the Luftwaffe possessed the forces described in the ultimatum. Nevertheless, the bluff was played - or perhaps the figures became exaggerated in later historical accounts.
The negotiator, Staff Officer Hauptmann iG Herre, set out for the Dutch headquarters behind the Bath Line at around 20:00 Dutch time, when darkness had already fallen. His four-man party was warned by forward SS outposts to avoid the main causeway, which was believed to have been mined. Following this advice, the Germans made their way cautiously into what they assumed was enemy-held territory. To their astonishment, they found no sign of a military presence. The entire line appeared deserted. Delighted by this discovery, they quickly turned back and reported the news before dawn on 15 May.
Some time later, but still early that morning, a couple of patrols of SS Standarte Deutschland cautiously approached the Bath Line. When they confirmed that the trenches and foxholes were indeed empty, they advanced rapidly through the position. A handful of Dutch defenders, unaware of the general withdrawal, were taken prisoner. Other SS troops quickly followed suit. At approximately 06:00 hours, the first German troops of the battle group under Oberstleutnant Kleinheisterkamp reached Krabbendijke, a position situated between the Bath Line and the Zanddijk Line.
The composition of the German force that eventually reached Krabbendijke is known in considerable detail from surviving German marching orders. It consisted of all three battalions of the SS Regiment Deutschland, together with the regiment's support units. In addition, the force included the SS Artillery Regiment, equipped with twelve 105 mm field howitzers, and a battery of II./Artillerie-Regiment 54, armed with four 150 mm howitzers.
Further support was provided by elements of the SS Panzerjäger-Abteilung, in total fielding thirty-six 37 mm PaK 36 anti-tank guns, and the SS Flak Battalion, equipped with twelve Rheinmetall 20 mm anti-aircraft guns. The force also included the SSPionier-Abteilung, comprising two companies of combat engineers with bridging equipment and assault boats, as well as two batteries of heavy Flak from I./Flak-Regiment 49, equipped with eight (soon to be) notorious 88 mm guns.
A platoon of armoured cars and motorised infantry from 3./SS-Aufklärungs-Abteilung, the divisional reconnaissance battalion, completed the formation. In total, the force numbered approximately 6,000 men. Its firepower was formidable, particularly when one considers that all of the Flak guns, including the heavy 88 mm pieces, were fully capable of engaging ground targets too, with devastating effect.
From the positions of the Zanddijk Line, the first German reconnaissance patrols were observed at approximately 08:00 hours. Their appearance came as no surprise. During the previous evening and night, elements of the retreating Dutch 14th Border Infantry Battalion had withdrawn through the bridges spanning the canal and had already reported the German advance. The defenders therefore knew that contact with the enemy was imminent.
The fall of the Bath Line had opened the eastern gateway to Zuid-Beveland. The Germans had advanced far more quickly than anticipated and now stood before the main defensive position on the island. The Battle of the Zanddijk Line was about to begin.
The Zanddijk Line (Zanddijkstelling) formed the principal defensive position defending the central islands of Zeeland. As noted earlier, it was a prepared defence line with a degree of depth and extensive inundations in front of it. Only five elevated routes crossed these flooded areas. The most important were the railway embankment and the main causeway, the Tholseindsche Dijk.
The defence consisted of two trench systems: a forward line and a stop line. Permanent fortifications were limited to three concrete casemates near the sluice complex in the south and two casemates on either side of the railway embankment. The remainder of the position comprised trenches, dugouts, and field fortifications reinforced with timber and earth. In addition, a considerable number of small but carefully concealed minefields had been laid at key points along the likely avenues of approach.
The composition of the defending force had changed several times during the preceding days. The trenches and foxholes were occupied by three battalions of the Dutch 40th Infantry Regiment, consisting largely of older reservists whose morale had been eroded by days of continuous air attacks and by news of the capitulation elsewhere in the Netherlands. These troops were supported by four modern 81 mm Stokes mortars, forty heavy machine guns, four modern Böhler 47 mm anti-tank guns, and six 57 mm Krupp infantry guns. In total, a little under 2,000 men defended the line.
The artillery available to support them consisted of twelve obsolete Krupp 84 mm 8-staal field guns, two more modern 105 mm field guns, and twelve relatively modern Krupp 75 mm 7-veld field guns. A battery of modern Vickers anti-aircraft guns was stationed some distance behind the front. In addition, three batteries of French soixante-quinze 75 mm field artillery were present, although they were not integrated into the Dutch chain of command.
Shortly before the battle began, the twelve 8-staal guns - who had an equal fire power as one battery of four Krupp 7-veld field guns - had been redirected towards the north following French instructions and were therefore unavailable for immediate support. Behind the canal west of the Zanddijk Line, two battalions of the French 271st Infantry Regiment and a Dutch company were positioned as a tactical reserve.
On paper, two formidable forces were about to clash along this narrow strip of land. Although German firepower clearly exceeded that of the combined Dutch-French defenders, the latter enjoyed the advantages of a well-prepared defensive position protected by inundations that severely restricted the enemy's freedom of manoeuvre.
The initial German attack was carried out by Gefechtsgruppe Kleinheisterkamp, a battalion-sized task force reinforced by the 15th Company Kradschützen of SS Regiment Deutschland, together with mortars and 75 mm short barreled infantry guns. After passing through Krabbendijke, the force advanced along the narrow Tholseindsche Dijk, the principal causeway through the flooded terrain.
After advancing only a few hundred metres, the Germans entered a pre-arranged killing zone. Dutch machine guns and mortars opened fire, halting the advance. SS troops scrambled down the embankment in search of cover, only for one squad to stumble directly into a minefield laid days earlier. A series of powerful explosions killed and wounded numerous men. Elements of the SS reconnaissance battalion probing the road towards Yerseke also suffered casualties from cleverly laid mines.
The exceptionally heavy Dutch mines - in this instance tweaked former 15 cm Werfer Granate from the WWI era - blasted craters several metres wide into the ground. The devastation left a profound impression on the German troops and contributed to what might be described as a growing fear of mines during the subsequent fighting in Zeeland. Given that virtually all German troops advancing westward were forced to use the same narrow causeways, the huge craters and the mutilated bodies left near the minefields served as a constant reminder of the danger until extensive clearance operations could be completed.
German engineers were brought forward and, under cover of machine-gun fire, began clearing lanes through the minefields. After this unwelcome delay, the assault resumed.
Approximately four German artillery batteries opened fire on the Dutch positions, concentrating particularly on the sectors flanking the Tholseindsche Dijk. The SS infantry advanced by bounds, moving forward in short rushes. As they neared the Dutch positions and turned northwards along the dike, additional mines claimed further casualties.
Meanwhile, Allied naval gunfire attempted to disrupt the German advance. Three warships, including the French destroyer L'Incomprise and a Dutch gunboat, shelled the approach routes. However, accurate fire proved difficult to achieve from rolling and pitching naval vessels. Many shells fell short or overshot their targets. The effectiveness of the bombardment improved somewhat when the twelve guns of III-17 RA were brought back into action, but the lack of forward observers meant that much of the fire remained inaccurate. But the artillery still made an impression on the German attackers that felt vunerable.
Without Luftwaffe intervention, the German assault might well have failed. At the very moment the attack began to lose momentum, a large formation of bombers - probably Ju 88s - appeared overhead and launched a concentrated attack against the northern and central sectors of the Dutch line. Simultaneously, a German artillery battalion intensified its bombardment. Luftwaffe Fighters repeatedly strafed the trenches. The brunt of the attack fell upon the sector held by the 3rd Battalion of the 38th Infantry Regiment.
Under this relentless combined assault, many defenders broke. Men began abandoning their positions, and their example quickly spread panic through neighbouring units. The leading German assault groups did not immediately realise that the defence was collapsing. They too had taken cover during the bombardment, while Allied artillery continued shelling the area around them. Only when the fire gradually slackened did they move forward again.
The delay proved crucial for the Dutch defenders. It provided sufficient time for the troops in the northern sector to withdraw across the northern canal bridge, known as the Postbrug. Most of their heavy weapons had to be abandoned. Not until the evening did Gefechtsgruppe Kleinheisterkamp reach the bridge, which by then had been destroyed. The south side of the line still held, but for how long?
The German losses during the assault were relatively light. Gefechtsgruppe Kleinheisterkamp suffered twenty-two killed in action, sixteen of whom fell in the minefields. Still, with a few dozen wounded the Germans had lost about half a company worth. Yet, considering that the attackers had been forced to advance along a narrow dike offering little room for manoeuvre, these losses were modest. The twelve Dutch guns of III-17 RA alone fired approximately 1,100 shells at the Tholseindsche Dijk, while Allied warships added substantial fire support. Still, only six German fatalities resulted from causes other than mines.
Dutch casualties were similarly limited, amounting to just seven dead. This illustrates that the intense German artillery and air bombardment inflicted relatively few physical losses. Its decisive effect was psychological. The defenders abandoned their positions not because they had been destroyed, but because they had been overwhelmed by the sheer violence of the attack and the lack of concrete strongpoints made them feel vulnerable.
Thus, the greater part of Zeeland's main defensive line was lost after a single determined combined-arms assault. As elsewhere in Europe during the spring of 1940, the Luftwaffe demonstrated that even well-prepared defensive positions could be broken through psychological shock as much as by physical destruction. Soldiers who could endure prolonged artillery fire often found the screaming dive-bombers, exploding bombs, and relentless strafing attacks far more difficult to withstand.
The same lesson was being demonstrated simultaneously at Sedan in northeastern France. There, a heavily fortified French position defended by substantial forces and powerful artillery had also been penetrated. On 13 May alone, German bombers flew roughly 1,250 sorties against the Sedan sector - an unprecedented concentration of air power. French infantry, artillery, and cavalry formations were systematically shattered, largely through Luftwaffe attacks. Even French armoured counterattacks were effectively neutralised by Stuka dive-bombers, despite significant German tank losses.
German air power was one of the decisive factors behind the success of the 1940 campaign, and Zeeland proved no exception. By 16 May, German armoured forces in the north of France were already approaching Montcornet, where they would encounter the last serious French resistance before northern France lay open before them. In Zeeland, meanwhile, the Germans had broken through the last organised defensive position. There was now little left that could halt their advance.
The Dutch troops withdrawing from the Zanddijk Line encountered considerable difficulties in crossing the canal that ran behind the position. French units of the 271st Infantry Regiment, stationed along the western bank, frequently mistook the retreating Dutch soldiers for German troops and opened fire on them. Matters were further complicated by the fact that the French had already demolished two of the bridges before all Dutch units had managed to cross. Only the northern bridge remained intact.
In the southern sector, a wire cable had been stretched across the canal to assist a small flat-bottomed ferry. Soldiers could board the boat and pull themselves across by hand. The process was painfully slow, prompting many men to attempt crossing further north. Not all succeeded in reaching safety.
The wounded had been evacuated to Goes, the largest town behind the line. The Dutch authorities had declared Goes an open city, meaning that military personnel were not permitted to enter it and that it would not defended, just shelter refugees and wounded. It had a large military emergency hospital. Consequently, retreating troops were required to bypass the town. The French would later disregard this restriction, but for the Dutch it remained in force.
The only part of the Zanddijk Line that was not immediately abandoned was the southern sector. Here, the defending battalion had largely escaped the devastating Luftwaffe attacks that had shattered morale elsewhere, and discipline remained intact. When a German reconnaissance force consisting of four armoured cars from 3./SS-Aufklärungs-Abteilung, accompanied by a squad of motorcycle infantry, suddenly appeared in front of the position, the Dutch defenders opened fire. A request for artillery support was immediately granted by the Dutch 7-veld batteries, while the French destroyer FS L'Incomprise also contributed naval gunfire. The German infantry took cover as the armoured cars cautiously edged forward.
Rather than withdrawing, the Germans reinforced their forward elements and continued pressing the attack. After approximately two hours of fighting, the Dutch outposts were ordered to fall back to the main defensive position. Their losses amounted to a single man killed in action.
By 13:00 hours, the determined SS troops had advanced to within less than a kilometre of the main defences of the Zanddijk Line. As German machine-gun and mortar fire intensified, some Dutch soldiers began to withdraw on their own initiative. The pressure steadily increased, and at 14:00 hours orders were issued to evacuate the southern sector.
The battalion - or what remained of it after numerous individual withdrawals - retreated in haste, abandoning much of its equipment and heavy weaponry. In some instances, Dutch soldiers simply handed their machine guns to French troops defending the canal line, effectively telling them: "They're yours now."
Only eight hours after the first German troops had appeared before the Zanddijk Line, Zeeland's principal defensive position had been abandoned by all its defenders. German fire had killed no more than eight Dutch soldiers.
The French author Lerecouvreux may have overstated his case when he described the Zanddijk Line in "L'Armée Giraud" as a "caricature de défense en profondeur" - a caricature of a defence in depth. The fortifications themselves were not without merit. The inundations, minefields, prepared positions, and restricted avenues of approach provided a reasonable basis for defence.
Yet where Lerecouvreux's criticism carried more weight was in his assessment of the defence itself. The line had not been overwhelmed by superior force. Rather, it had been abandoned after comparatively light casualties and before the Germans had succeeded in mounting a full-scale assault against most sectors. The decisive factor was not the destruction of the position, but the collapse of confidence among many of its defenders.
The fall of the Zanddijk Line marked the end of organised Dutch resistance in Zeeland. From that moment onward, the burden of continued defence would fall increasingly upon the French forces that remained in the province.
The two prepared defensive lines in Zeeland - the Bath Line and the Zanddijk Line - had both succumbed rapidly to the first serious German pressure. The entire sequence of events had unfolded in less than twenty-four hours. Dutch losses amounted to only ten men killed in action, while German casualties totalled approximately thirty dead, two-thirds of whom had fallen victim to the carefully laid Dutch minefields.
The result was that, by 15:00 hours on 15 May, the narrow Zuid-Beveland Canal had become the new front line. Along its western bank, battalions of the French 271st Infantry Regiment anxiously awaited the next German move. The soldiers dug in behind the low canal embankment, preparing to defend the position as best they could.
The French troops were far from ideally equipped for the task. Much of their heavier equipment was still in transit, a circumstance that reflected the speed with which events had developed. Few could have anticipated that the two Dutch defensive lines would collapse within a single day. As a consequence, the infantry possessed only three 2,5 cm Hotchkiss anti-tank guns and a handful of 60 mm mortars as their principal heavy weapons.
Additional support remained available. Three batteries of French 75 mm field guns could provide artillery fire, while Dutch and French naval vessels operating in the surrounding waters were capable of delivering gunfire support. Yet these assets were of limited value without effective communications. Coordination between the various French, Dutch, and naval elements was often unreliable, and the command structure remained far from ideal.
As evening approached, the French soldiers along the canal found themselves facing an uncertain future. They occupied a hastily assumed defensive position, lacked much of their heavier equipment, and knew that the Germans had already swept aside the prepared Dutch defences with alarming speed.
The canal line represented the last organised obstacle on Zuid-Beveland. Beyond it lay the route to Walcheren and the heart of the remaining Allied position in Zeeland. The question that weighed heavily on the minds of the French defenders was simple: what would the Germans bring against them the following day?