German artillery, contrary to the usual picture of the Normandy beaches gathered from films like Saving Private Ryan, was the largest cause of casualties on D-Day. However, it was unable to repel the landings. There were several reasons for this, from the obsolescence and paucity of the German guns to the Allied attempts to neutralise them.

The Normandy coast was one of the less well-defended sectors of the French coast. While there were heavy German batteries around the port cities of Le Havre and Cherbourg, much of the coastline was poorly protected. The Pas de Calais, closer to the UK, was seen as a more likely target for an amphibious landing. Therefore, it had received priority for defences. The Normandy coastline had been neglected. Similarly, the areas around the major ports had been prioritised, unlike the empty coastline. Of the ~100 miles of the invasion front, there were 25 batteries of various sizes. These coastal batteries mostly had smaller guns, of a 3.9-6in calibre. The largest were the 210mm (8.3in) guns at Crisbecq and the 380mm (15in) gun at the Le Grand Clos battery near Le Havre. Beyond the coastal defences were the artillery batteries of the units assigned to defend the coast. These were the 352nd and 716th Infantry Divisions, plus elements of the 709th around Utah. These divisions typically had three artillery batteries, armed with 75mm or 105mm guns, as well as mortars at lower levels of the chain of command. To destroy an invasion, these guns had to be able to sweep a vast amount of space. They had to cover the beaches themselves, but also the area inland of them, to catch paratroopers and troops that had made it off the beaches. They had to cover the sea beyond the beaches, out to the range of the Allied battleships. This was impossible, given the relative lack of firepower.

Compounding this was the obsolescence of the guns themselves, and the poor state of their maintenance and mountings. Almost every gun on the coast had been captured, either from the Czechs, the French or the Russians. Some of them were WWI-era, or even older. Some had been poorly maintained. A German soldier assigned to the gun battery at Colleville-sur-Orne noted streaks of rust on the battery's four 100mm guns. The guns had slower rates of fire than more modern guns, while the poor maintenance reduced their accuracy. The gunners were, especially in the 716th's sector, conscripted Poles, Czechs and Russians. They were unwilling to work hard for the Germans, and often gave up under fire. While the Germans had planned to mount many of the guns in concrete bunkers, to protect them from Allied bombardments, this was a slow process. The Calais area, and the ports, were a key priority for bunker construction, and concrete and steel were diverted there. Many of the batteries were incomplete, or uncovered altogether. The battery at Crisbecq had bunkers for only two of its three 210mm guns. Le Grand Clos was due to take three 15in guns, but only one had been installed by D-Day. Several of the batteries hadn't had their guns installed. Most notably, the battery at Pointe du Hoc was empty; the guns meant for it were inland. Other batteries had positioned their ammunition stores in covered bunkers away from the guns. While this was safer, trucks carrying ammunition were easy targets for Allied fighter-bombers on D-Day; this caused at least one battery to run out of ammunition and fall silent.

The Allies put a large amount of effort into neutralising German artillery positions. Every battery on the coast had received some attention from the Allied air forces in the run-up to the invasion. However, this had been limited, to avoid inadvertently informing the Germans where the Allies were to attack. On the 6th, the Allies used every tool in their toolbox to destroy or suppress the batteries. The most threatening batteries were attacked directly. The battery at Merville, threatening the eastern flank of Sword Beach, was attacked by elements of the British 6th Airborne Division. Similarly, the Pointe du Hoc battery and a 75mm battery at Point de la Percee were attacked by US Rangers. Other batteries were attacked on an ad-hoc basis. The battery at Brecourt Manor, for example, was not a planned target for the American 101st Airborne, but was a target of opportunity. Batteries that were not attacked by troops were attacked from the sea and air. D-Day opened with a vast bombing raid, with heavy and medium bombers attacking targets along the coastal strip. While accuracy was poor, it helped to suppress the gun batteries and cut the phone lines linking them with their observers. After this came the vast naval bombardment. The Allies had assigned five battleships, two monitors and 21 cruisers to the bombardment force, plus the Dutch gunboat Soemba. These ships were tasked with suppressing the heavier coastal batteries behind and to the flanks of the landing. The batteries immediately behind and around the beaches were targetted by the 57 destroyers of the bombardment force, as well as by the various armed landing craft and self-propelled guns in landing craft. The naval bombardment was more accurate than the aerial attack, but still left much to be desired. Even so, they were able to suppress and disable most of the coastal batteries. The battery at Longues-sur-Mer had three of its four guns knocked out by Allied cruisers, including one destroyed by a direct hit from HMS Ajax, while the battery at Crisbecq was disabled by 15in fire from the monitor HMS Erebus. Once the troops were ashore, a number of the batteries quickly fell. The battery at Colleville-sur-Orne was captured at 11:30 by British troops advancing inland from Sword Beach, without having fired a shot. The battery at Mont-Fleury, hammered by fire from Belfast and Orion, similarly surrendered almost as soon as troops from Gold Beach reached it.

The Allied bombardment significantly damaged or disrupted many batteries on the coast, but it also had a more subtle effect. The scale of the bombardment drew German gunners into firing on the bombarding ships, and not on the transports and landing craft. This was, arguably, a mistake. While the warships were firing on the gun batteries, they were more manoeuvrable and better protected than the transports. The guns, poorly laid, and with their observers disrupted by the bombardment of the beaches, were relatively inaccurate. Only one ship can be claimed by the shore batteries. This was the American destroyer Corry, sunk off Utah beach by the Crisbecq battery. This toll could have been much higher had the batteries chosen to fire on the transports moored further out. Field guns and mortars fired on the beaches throughout the landing, and did cause many casualties. However, there were too few of these to do more than provide harassing fire.