Fort Eben-Emael was part of the defences along the Belgian–Dutch border, providing artillery cover for two of the three key bridges in the area crossing the Albert Canal. As part of the German plan for the invasion of France through the Low Countries, the elimination of the fort would allow the bridges to be secured before the Belgian defenders had time to destroy them. After meticulous planning in great secrecy, the German attack was launched in the early hours of 10 May using 493 airborne troops and around 50 gliders. The forces were grouped together as the Sturmabteilung Koch and were split into assault groups Steel, Concrete and Iron which would secure the bridges, whilst group Granite was tasked with securing the fort. Although they were left without reinforcements until the evening of 11 May, assault group Granite achieved their objective of destroying the fort’s artillery emplacements, allowing two of the bridges to be secured before they could be destroyed.