As noted earlier, two prepared defensive lines had been constructed in Zeeland: the narrow Bath Line on the far east of Zuid-Beveland and the Zanddijk Line more to the west. We shall now take a closer look at the characteristics of these defences.
The first defensive line the Germans would encounter was the Bath Line, situated just west of the narrowest section (4 km wide) of the land connection to Zuid-Beveland, a fraction to the west of Woensdrecht. The village of Rilland lay closest to the position.
The line derived its name from the old fortress 'Bath' nearby, although the fortress itself was no longer operational. In reality, the 4 km stretching Bath Line consisted of little more than a defended anti-tank barrier, lightly reinforced with twelve small concrete machine-gun casemates. In front of the line, inundations had been created to hinder an enemy advance. Access to the position was possible only via two causeways: one in the south and the principal route running through the centre of the defence, formed by the main road and the elevated railway embankment.
The trenches and casemates were manned by approximately 400 soldiers of the 14th Border Infantry Battalion. The battalion possessed six heavy machine guns, three 4,7 cm Böhler anti-tank guns, and two light Krupp 5.7 cm infantry guns. In real numbers it came down to a 4 km stretch of defenses manned by a mere 100 man per kilometre, which was extremely low a number. The only reason this low number could work out was the fact that only very narrow approaches could be used by the opposing forces, causing the 400 defenders to be largely concentrated around these accesses.
The Bath Line was intended as a forward position covering the main defensive line at the Zanddijk Line. It lacked both defensive depth and land-based artillery support. Any artillery assistance was expected to come from naval units, in particular the modern gunboats Hr.Ms. Johan Maurits van Nassau and Hr.Ms. Flores, whose combined armament consisted of six 15 cm guns.
The 10 km long Zanddijk Line was situated between the small towns of Yerseke in the north and Kruiningen in the south, approximately fifteen kilometres west of the Bath Line.
The inundations in front of the position had been arranged in such a way that only five narrow approaches remained accessible. These access routes consisted primarily of raised causeways and dikes, each defended by heavy machine guns and infantry guns.
The line itself, stretching roughly ten kilometres in length, was occupied by three infantry battalions and one reserve border infantry company held in reserve, amounting to a total strength of approximately 2,000 men. The northern sector was defended by the 3rd Battalion of the 38th Infantry Regiment, the central sector by the 3rd Battalion of the 40th Infantry Regiment, and the southern sector by the 1st Battalion of the 40th Infantry Regiment. The troops manning these positions consisted largely of older reservists, many of them men well into their thirties. In reality, that higher average age differed not too much from the French units that would come to their aid.
The entire artillery strength of the Zeeland Territorial Command had been assigned in support of this line. This support consisted of three batteries of older Krupp 8-staal guns - whose combined effectiveness equalled roughly that of a single battery of four modern Krupp 7-veld guns - together with three batteries of 7-veld field artillery, two Krupp 10.5 cm guns, and a section of two 8,1 cm mortars. Additional support was provided by two Krupp 6-veld 5.7 cm infantry guns and thirty-one heavy machine guns. Modern anti-tank guns, however, were entirely absent in this line.
Air defence along the line was limited to a single three-gun battery of obsolete 7.5 cm anti-aircraft artillery positioned near the railway embankment. These older guns had a limited effective vertical range of around 4,500 m and only three rounds a minute rate of fire per gun. This small contingent wouldn't pose too much concern to enemy aircraft.
Although the Zanddijk Line did not possess great defensive depth, it had nevertheless been developed sufficiently to sustain a determined defence for a considerable period of time. The position consisted of a dual trench system, divided into a front line and a secondary stop line. The trenches themselves contained very little concrete reinforcement. Only five ferro-concrete casemates had been constructed: three light machine-gun positions near the sluices in the southern sector and two heavy machine-gun casemates covering the two principal causeways.
A major disadvantage of the line was that the planners had been compelled to construct it just east of the canal that cut through the Zuid-Beveland peninsula from north to south - the Canal through South Beveland. At first glance, positioning the defence on the western bank of the canal would have appeared the more logical choice, like General Durand had considered. However, the eastern bank of the canal was significantly higher than the western one. As a result, troops defending from the western side would have suffered from a severely restricted field of observation and fire.
This was a factor that the French General Durand would later dismiss as relatively unimportant during the campaign. For this reason, he refused to reinforce the Dutch positions in the Zanddijk Line and instead stubbornly deployed his troops on the western bank of the canal - a decision that would ultimately prove disastrous.
The manning of the line was not as strong as contemporary military doctrine prescribed, which generally called for one battalion per kilometre of defended front. Nevertheless, the inundations, the narrow approaches to the position, and the support of four to five artillery batteries combined to make the Zanddijk Line, at least on paper, a formidable defensive position for any attacking force to overcome.