The island of Schouwen-Duiveland played no significant role in either Dutch or French defence planning. Following the capitulation of the Dutch Army in the rest of the country, its strategic importance diminished even further. By then, the island no longer served any meaningful purpose in the wider conduct of the campaign.
On 10 May, the island's military presence had been modest. Its garrison consisted of a harbour battery with three Krupp 7,5 cm guns ('7 lang 40'), a platoon of infantry assigned to protect the battery, and Haamstede Airfield, together with its small complement of personnel and a company of guard troops. In addition, the 162nd Anti-Aircraft Battery, equipped with three 40 mm Bofors guns, was deployed between the airfield and the western coastline. Altogether, no more than approximately 250 men were available for any form of combat duty.
During the days that followed, however, a growing number of troops arrived on the island, also as a consequence of the deteriorating military situation elsewhere. Two guard companies from Gilze-Rijen Air Base reached Schouwen-Duiveland on 10 May on orders. Several days later, around one hundred soldiers withdrawn from the Peel-Raam Line arrived. On 15 May, a company composed of reorganised troops from Noord-Brabant was added to the garrison, while in the evening of 16 May another 250 men evacuated from Tholen reached the island.
As a result, the total Dutch military presence gradually increased to between 900 and 1,000 men.
On paper this reinforcement appeared to be a substantial force. In reality, however, it was little more than a collection of disparate detachments brought together by circumstance rather than design. Most of the troops consisted of retreating formations, rear-area personnel, airfield guards, or soldiers who had already experienced the collapse of the front elsewhere. They lacked heavy weapons, cohesive command structures, and, perhaps most importantly, confidence in the outcome of the campaign.
Consequently, despite the growing number of troops present, the military value of these formations remained limited. They possessed neither the equipment nor the organisation required to conduct sustained defensive operations against a determined German attack. Schouwen-Duiveland had become a refuge for fragments of defeated units rather than a fortress capable of influencing the course of the battle for Zeeland.
The island commander remained Captain De Ruyter van Steveninck, formerly the commanding officer of the now-evacuated Haamstede Air Base. He decided that the former airfield guard company would man the defensive positions along the Zijpe shoreline, directly opposite the German troops on St. Philipsland.
Although his options were limited, it remains remarkable that this particular unit was assigned to defend what was by far the most likely crossing point for a German assault. During the preceding days, the company had repeatedly demonstrated poor discipline and low morale. On one occasion, a substantial number of its men had disarmed themselves and dispersed into the dunes on the western side of the island, requiring considerable effort to locate and reassemble them. Despite this record, these troops were now expected to resist a possible German amphibious crossing, even though several more capable formations were available elsewhere on the island.
The remaining troops were dispersed across Schouwen-Duiveland in small detachments, many without a clearly defined role, detailed briefing, or coherent defensive plan.
The shortcomings of the airfield guard company soon became apparent. During the afternoon, German troops positioned near Anna Jacobapolder on St. Philipsland opened fire across the Zijpe with machine guns, anti-tank guns, and mortars. When one Dutch soldier was seriously wounded, the company commander immediately ordered a withdrawal some two kilometres inland, leaving only a small detachment in the town of Bruinisse as an advanced outpost.
The decision was highly questionable. By abandoning the coastal positions, the entire stretch of shoreline opposite the Germans was effectively left undefended. When Captain De Ruyter van Steveninck inspected the coastal defences later that evening, he discovered that the dike line was completely deserted. Continuing westward, he encountered the small forward detachment at Bruinisse. To his astonishment, some of the men had already attached a white flag to one of their rifles and appeared prepared to surrender at the first sign of a German approach.
Outraged, the captain immediately ordered the company back to its original positions along the coast. His reaction was understandable. Yet one may also question his continued confidence in a unit that had repeatedly demonstrated its inability or unwillingness to perform its duties. Rather than replacing the company with more reliable infantry available elsewhere on the island, he chose to retain it in the sector most likely to face a German attack. In his view, the matter had been resolved simply because he had succeeded in driving the men back to their posts.
The reality was less reassuring.
By this stage it had become painfully evident that any determined German attempt to cross the Zijpe and land on Schouwen-Duiveland would likely succeed before it had truly begun. The defenders lacked confidence, discipline, and effective leadership. Their positions may have been reoccupied, but the will to defend them remained highly questionable.