Still, even for expeditions below invasion strength the navy will only regard the army as a second line, and its strategy must provide in the event of evasion for co-operation with that line. By means of a just distribution of its coastal flotilla it will provide for getting contact with the expedition at the earliest moment after its destination is declared. It will press the principle of making the army its objective to the utmost limit by the most powerful and energetic cruiser pursuit, and with wireless and the increased ratio of cruiser speed, such pursuit is far more formidable than it ever was. No expedition nowadays, however successful its evasion, can be guaranteed against naval interruption in the process of landing. Still less can it be guaranteed against naval interference in its rear or flanks while it is securing its front against the home army. It may seek by using large transports to reduce their number and secure higher speed, but while that will raise its chance of evasion, it will prolong the critical period of landing. If it seek by using smaller transports to quicken disembarkation, that will decrease its chances of evasion by lowering its speed and widening the sea area it will occupy in transit. All the modern developments in fact which make for defence in case of invasion over an uncommanded sea also go to facilitate timely contact with an expedition seeking to operate by evasion. Nor must it be forgotten, since the problem is a combined one, that the corresponding developments ashore tell with little less force in favour of the defending army. Such appear to be the broad principles which govern an enemy's attempts to act with combined expeditions in our own waters, where by hypothesis we are in sufficient naval strength to deny him permanent local command. We may now turn to the larger and more complex question of the conduct of such expeditions where the naval conditions are reversed. By the conduct, be it remembered, we mean not only their defence but also their support, and for this reason the starting-point of our inquiry is to be found, as above indicated, in the contrast of combined expeditions with convoys. A convoy consists of two elements--a fleet of merchantmen and an escort. But a combined expedition does not consist simply of an army and a squadron. It is an organism at once more complex and more homogeneous. Its constitution is fourfold. There is, firstly, the army; secondly, the transports and landing flotilla--that is, the flotilla of flat-boats and steamboats for towing them, all of which may be carried in the transports or accompany them; thirdly, the "Squadron in charge of transports," as it came to be called, which includes the escort proper and the supporting flotilla of lighter craft for inshore work; and lastly, the "Covering squadron."