The exploits of the Dutch in the Thames and the Medway caused considerable alarm in London. Pepys, on hearing of the failure of the chain of Chatham, writes of it as a very serious piece of news, "which," he says, "struck me to the heart." Another and rather more precise account of the occurrence is as follows: On 12 June the Dutch sent up towards Gillingham a division consisting of four men-of-war, three armed yachts, and two fire-ships. Several of the ships charging at the same time, broke the chain, entered the waters beyond and set fire to the Mathias. The Dutch next dealt with the batteries at either end of the chain, and by means of their guns quickly silenced them. Great damage was done to the shipping in the Medway, many vessels being burnt and destroyed. It seems probable that at least one purpose of the chain was to hinder the progress of fire-ships which the enemy set in motion against our shipping. In order to defend the government works nearer London, batteries mounting sixty pieces of ordnance were erected at Woolwich, whilst the defensive works at Gravesend and Dover were strengthened. About the middle of the following September workmen were employed in clearing away the moorings of the chain at Gillingham Reach. _Chains at Portsmouth, Great Yarmouth, etc._--The chain of Chatham furnishes a curious example of coast defence, wholly ineffective against powerful shipping; but it was not a novelty. Portsmouth Harbour had been at an earlier period provided with a similar form of defence. Edward VI, on the occasion of a visit to Southsea Castle, determined to strengthen Portsmouth against invasion by the enemy. He therefore directed the building of two massive towers at the entrance to the harbour. To these an immense iron chain was fixed in such a way that it could be raised and tightened or lowered at pleasure when the approach of the enemy made this desirable. The fortifications of Portsmouth were strengthened during the reign of Elizabeth (see p. 145). _Great Yarmouth._--In addition to a boom and two timber jetties at the entrance to the haven, Yarmouth possessed a chain for the protection of its shipping. _Hull_ possessed a chain, and an actual picture of it is preserved in one of the Cotton MSS. _Cowes_ also was defended by a chain. _Fowey._--For the protection of this town Edward IV erected two towers to carry a chain which was suspended, doubtless under the level of the water, across the haven, or mouth of the River Fowey. Subsequently the people of Fowey incurred the royal disapproval when they attacked the French during a truce, and accordingly Edward IV had the chain removed and sent to Dartmouth. It does not seem quite clear whether this chain, when removed to Dartmouth, was used for the protection of shipping, but there certainly was a chain bridge at this place in which, conceivably, the old chain may have been utilized.