The sea battle at Sluys, present-day Netherlands, was the first major confrontation of the Hundred Years War. On June 24,1340 an outnumbered English fleet approached the anchored French "Army of the Sea" which included ships and soldiers from Genoa, Castille, and other allies.
The next major confrontation of the "war" was in 1346 at the Battle of Crecy:
You can also see the Lego Battle of Agincourt, 1415, here: https://www.youtube.com/watch?v=X8LZ5o39KkQ
King Edward III of England led the English fleet in person aboard his Cog "Thomas" and he was injured in the leg during the fighting. The French fleet was commanded by Hugues Quiret.
Against Genoese advice the French decided to chain their ships together and remain anchored. The English ships were filled with archers and shot French men off the decks. Then the French ships were boarded and captured or destroyed.
After Sluys the French coast was open to invasion by England.
The French Chronicle of London, written nearly at the same time as the battle, reports at 14 Edward III (A.D. 1339, 40) that:
"The wind had then been in the East for the whole fortnight before the King put to sea, but by the grace of Him who is Almighty, the wind shifted immediately to the West; so that, by the grace of God, the King and his fleet had both wind and weather to their mind. And so they sailed on until sunrise at break of day; when he saw his enemies so strongly equipped, that it was a most dreadful thing to behold; for the fleet of the ships of France was so strongly bound together with massive chains, castles, bretasches, and bars. But notwithstanding this, Sir Edward, our King, said to all those who were around him in the fleet of England, 'Fair lords and brethren of mine, be nothing dismayed, but be all of good cheer, and he who for me shall begin the fight and shall combat with a right good heart, shall have the benison of God Almighty; and every one shall retain that which he shall gain.'
And so soon as our King had said this, all were of right eager heart to avenge him of his enemies. And then our mariners hauled their sails half-mast high, and hauled up their anchors in manner as though they intended to fly; and when the fleet of France beheld this, they loosened themselves from their heavy chains to pursue us. And forthwith our ships turned back upon them, and the melee began, to the sound of trumpets, nakers, viols, tabors, and many other kinds of minstrelsy. And then did our King, with three hundred ships, vigorously assail the French with their five hundred great ships and galleys, and eagerly did our people exert great diligence to give battle to the French. Our archers and our arbalesters began to fire as densely as hail falls in winter, and our engineers hurled so steadily, that the French had not power to look or to hold up their heads. And in the meantime, while this assault lasted, our English people with a great force boarded their galleys, and fought with the French hand to hand, and threw them out of their ships and galleys. And always, our King encouraged them to fight bravely with his enemies, he himself being in the cog called 'Thomas of Winchelsee.' And at the hour of tierce [about 9 am] there came to them a ship of London, which belonged to William Haunsard, and it did much good in the said battle. For the battle was so severe and so hardly contested, that the assault lasted from noon all day and all night, and the morrow until the hour of prime [about six in the evening]; and when the battle was discontinued, no French man remained alive, save only Spaudefisshe, who took to flight with four-and-twenty ships and galleys."
More information about this battle and the lead-up to the Hundred Years War can be found at: