“And that’s the only way you can get into Inchon?” Howe asked.
“Yes, sir. That’s one of the problems the invasion fleet is going to face, moving forty-five miles, and moving slow— the channel twists and turns, and in some parts you have to move at steerage speed—”
“Which is?” Howe asked.
“The slowest speed at which you have steering ability,” Pickering answered for him. “And the channel is not very wide; it’ll mean moving the ships most of the way in a column. ”
“And that means, sir,” Taylor said, “the chances of surprising anyone at Inchon are pretty slim.”
“Just for openers, it seems like a lousy place to stage an amphibious invasion,” Howe said.
“And we haven’t even touched on the tides yet,” Pickering said.
“Tell me about tides,” Howe ordered, “in very simple terms.”
“You know, sir, that tides are cyclic?” Taylor asked.
“Not enough. Tell me,” Howe said.
“In the Atlantic Ocean, there’re two tides a day—they call that semidiurnal. A tidal day is twenty-four hours and fifty minutes. When the tides are semidiurnal, that means you get high tide at, say, six o’clock in the morning, low tide a little after noon, and another high tide at about six-twenty-five that night, and another low tide six hours and twelve minutes after that.
“In the Pacific, there’re both semidiurnal tides and diurnal, which means that you get high tide at six in the morning, low tide twelve hours and twenty five minutes after that, and another high tide the next morning at ten minutes to seven.”
“And that’s what it is at Inchon?”
“Not exactly, sir. What they have at Inchon is mixed tides, which means that sometimes the moon and the sun are both acting on the water at the same time. And what that means is that the tides are huge. At Inchon, high tide is sometimes thirty feet above normal sea level, and at low six feet below normal. That means a difference of thirty-six feet. That’s at the high end of the cycle.”
“What does that mean?” Howe asked. “High end of the cycle?”
“There’s a monthly cycle to tides, twenty-eight days, like the lunar cycle,” Taylor explained. “At the high end of the cycle, at Inchon, high tide is sometimes thirty feet above sea level, and low, six feet below. At the low end of the cycle, high tide is maybe twenty feet above normal, and maybe four feet above at low tide.” Taylor paused. “This is twice a day, you understand?”
“You may have to explain it all over again, but go on, what does this mean?”
“Sir, it means that at low tide, all these areas here, from the mainland shore, and around the islands, don’t have any water over them. . . .”
“Mudflats, Ralph, miles and miles of mud,” Pickering said.
“Which means,” Taylor explained, “that the invasion would have to take place at high tide at the high end of the monthly cycle. Maybe a day, either way, but no more than a day.”
“I don’t understand that,” Howe said.
“You need the highest tide you can get, to get the ships through the channel into Inchon, and then get them out again,” Pickering said. “And you have the highest tides only on one day a month.”
“Jesus!” Howe said.
“Even then, there’s no way that I can see that they can get every vessel in and out, sir,” Taylor said. “Maybe they can get one or two attack transports in there, unload them, and get them out on one tide, but there’re going to be LSTs and everything else stuck in the mud.”
“I agree,” Pickering said. “Stuck until the tide comes in again and refloats them.”
“When do we get a high tide? Is that the correct term?” Howe asked.
“August eighteen is the next one, sir, and the one after that is 15 September. That’s what they’re shooting for, 15 September.”
Howe looked at Pickering.
“So ‘when I will land’ at Inchon is September fifteenth?”
“It would appear to be,” Pickering said.
“Is there more bad news, Mr. Taylor, about this brilliant invasion idea? Or have I heard it all?”
“Not quite, sir,” Taylor said.
“Jesus! What else can go wrong?”
“Sir, if you look here,” Taylor said, pointing at the map. “You see this little island here, Paega-do? It’s about five miles off the mainland. The water between it and the mainland is fifteen, sometimes twenty, feet deep at high tide. At low tide, it’s a mudflat. From the west side of Paega-do, it’s about five miles to Yonghung-do. The Flying Fish Channel, half a mile wide, runs north-south through there, mostly right