[jason taylor]

Most ships, certainly most purpose built warships were capable of being beached. Perhaps not a giant roman bread vessel, or one of those monster warships of the Macedonian Succession Wars that they were so ridiculously fascinated with and did little good to anyone but Archeologists. But a typical Venetian galley or Norse longship, or a Macdonald Berlinn(Scotch galley) could do so and would routinely on various missions. No Ancient or Medieval power needed specialized landing craft as such very much.

What was needed was something that could carry the horses and heavy impedimenta of a first class army. But back country polities like the Norse and the Macdonalds wouldn't have such amenities, and powers like Venice that were chiefly maritime would place lower priority on them.