The English are famously nostalgic about their naval tradition, which mostly comes from the late age of sail, 1750-1850. During that era, ships were invariably built from wood, and the sailors who crewed them are, in imagination and literature, depicted as strong and unyielding- like steel. "Wooden ships and iron men" is something of a cliche in referring to that era.
The C&H cartoon imagines an old man reminiscing about the past, and suggests that he's alluding to that era of wooden sailing ships. But his further comment in the third panel reveals that he's really talking about an (imaginary, of course) battle between a navy with wooden ships and cyborgs- men literally made of steel: robots.