Her cannon could fire 250 kilograms of ammunition in a single broadside, and when the heavy iron shot left the muzzles, they travelled near the speed of sound. For a brief few minutes, she was the most powerfully armed ship in the Baltic, if not the world, a floating fortress to be feared from Reval to Copenhagen.
Vasa carried 64 cannon when she set off on her maiden voyage in August 1628, but eight of the gunports were empty; the navy yard could build a ship faster than the royal gun foundry could cast its guns. The main armament was 48 24-pounders, powerful bronze cannon that fired round shot weighing ten kilograms each. The upper deck carried smaller cannon: eight 3-pounders (1.25 kg) and six stormstycken, short, thin-walled guns for firing anti-personnel ammunition at short range.
The 24-pounder was a new type of gun developed in 1620 for the army as mobile siege artillery. It weighed only half of the traditional naval 24-pounder, and was part of the king's drive to standardize the weaponry of both the army and navy to make it easier to manufacture and supply ammunition.
The cannon on either side of the ship could fire a broadside of 250 kilograms (not counting the stormstycken), around four times as much as the typical Swedish warship of the 1620s, and twice as much as the largest ships in other northern European navies. Had she been able to carry sail, Vasa would have been a fast ship, and this combination of speed and firepower could have been devastating.
Tactics old and new
Vasa represents a conflict within the Swedish navy over how warships should be used. Traditional officers believed that the deciding moment of a sea battle came in boarding and capturing the enemy, since it was better to take an enemy ship into the Swedish fleet than destroy it. They wanted a ship which could carry a large crew, armed with pikes and axes, and cannon were only used to disable a ship and demoralize its crew. Gustav Adolf, who was a keen artillerist, saw a future in which sea battles would be artillery duels. For him, the cannon was the primary armament, and so he preferred more guns and bigger guns. He ordered a number of ships like Vasa, big and heavily armed, but almost all of these orders were cancelled after he died, as the navy did not want such ships.
Vasa carried a large armament, but it also carried a large crew, two thirds of them soldiers, who could man the guns but who could also be used to overwhelm an enemy in a boarding action. Among the artefacts found in the ship are not only the cannon, but boarding axes, short, tomahawk-like weapons which could be used both for clearing obstructions and in hand-to-hand combat.
The guns could fire several different types of ammunition. Round shot were the most common, used to damage the enemy ship and create clouds of splinters wounding men over a large area. Crossbar shot (a round shot with a large spike in it) and scissor shot (crossbar shot in two pivoting halves, which opened in midair to form a wicked cross) were used at longer range against enemy sails and rigging, to slow down and cripple the enemy so the he could not escape or maneuver. Chain shot (two half shot connected by a chain) opened in midair and were used at short range to destroy rigging and sails. Case shot (a wooden tube filled with musket balls or scrap metal) was used at short range, especially in the stormstycken, to cut bloody swaths through enemy crew massed on the decks just before boarding. Men positioned in the tops with muskets could also act as sharpshooters, to eliminate enemy officers.
Sea battles in this time did not involve coordinated fleets, but quickly dissolved into a series of individual duels between ships. The idea of massed fire from several ships at a common target was still a generation in the future. The largest ships in each fleet would seek each other out, pairing up to slug it out in a contest of will, skill and stamina.
Even in an artillery duel, capturing a ship required boarding the enemy and subduing the crew. This could be the bloodiest part of the day, as men fought each other at close quarters with axes, pikes and swords. In the Swedish navy, losing a ship to the enemy was considered so disastrous that it was official policy that a ship should be blown up if about to be captured, rather than have it fall into enemy hands.
Preparations for battle
Fire was one of the greatest risks at sea, and especially in battle. No loose gunpowder was allowed in the gundecks, and individual charges were only brought up one at a time. The galley fires were extinguished and water pumped over all the decks to soak the wood. Sailors climbed into the rigging with buckets to wet down the sails. Buckets of water and sand were placed near the guns, along with wet hides, to extinguish fires before they could spread.
The men were also prepared, in both flesh and spirit. Church services were held, so that those who fought might hope for His help in the struggle and His grace if they died. For those who took their courage in more physical form, an extra ration of beer might be served, and in 1628, Vice Admiral Henrik Fleming had purchased extra beer of good quality with his own money for this purpose.
Blown to kingdom come
Although Gustav Adolf concentrated substantial resources on building up his navy, it only fought one battle in the 1620s. In November 1627, at Oliwa, on the Polish coast near Gdańsk, the Polish fleet attempted to escape the Swedish blockade of the port and attacked the two ships at the end of the Swedish line. Tigern, the Swedish flagship, was captured, with the loss of two-thirds of the crew of 210 after a desparate boarding action. One of the dead was the Vice Admiral Nils Göransson Stiernsköld, who was hit by musket balls in his back and neck, but nevertheless kept fighting. Finally, a cannonball tore off his left arm, and he died shortly afterwards. The commander on the Polish side, Admiral Arndt Dickman, was also killed by a cannonball. The crew of Tigern had attempted to blow up their ship, but the man carrying the lighted match to the gunpowder charges was cut down. The crew of Solen succeeded in igniting their charges, and the ship disintegrated in a towering explosion. Its remains have been excavated by the Polish National Maritime Museum, and the guns and sailors' possessions are now on display in Gdańsk.