The surveying vessels were often forced to remain within the danger zone of the German batteries, and, owing to shortness of time, had to utilise every possible opportunity for fixing positions of buoys, taking soundings, examining areas where new shoals were suspected, marking the limits of old shoals, laying down special marks to assist the passage of the expedition, and to enable the bombarding vessels to take up their positions with accuracy. Old obstructions had to be removed and wrecks had to be correctly charted. The vagaries of the weather rendered the task all the more difficult, and interference from the enemy was experienced on more than one occasion. Incidentally both these officers were on board H.M.S. _Botha_ when she rammed and sank the German torpedo-boat A-19, which was out with a few others on one of their very infrequent tip-and-run escapades off Dunkirk; this was a pleasant interlude for these hard-worked officers. No country in the world can boast of such an efficient Hydrographic Department as our own. Their work in the war passed almost unrecorded, but none the less appreciated by those of us "who went down to the sea in ships." No praise could be too great for the work of the surveyors employed on our behalf. It will be readily understood that little reliance could be placed on large conspicuous buoys laid by us near the enemy's coast. On discovering such navigational marks the enemy would presumably either move them a mile or so, for the purpose of interfering {92} with our navigation, or else remove them altogether. Buoys, to be of any practical use, must be conspicuous, hence the likelihood of their being seen by the enemy unless placed in position at the last possible moment. This alternative was actually followed; it does not require much imagination to realise the difficulties and dangers in placing them in readiness for the operation and in removing them again on each occasion when the operation was postponed.