The vanishers

Trapped, facing an incredible shadow army, whose lightest touch meant instant dissolution—the last fighters of invaded Earth made their bitter choice—victory beyond death's portals—or oblivion!
CHAPTER ONE
The Invisible Wall
My men were in battle dress for the landing—steel helmets painted green, dirty green jackets, pants, cartridge belts, heavy field shoes. The Caribbean was so deep blue it hurt the eyes. You could look straight down into it until it made you dizzy. Sharks, some of them monsters, congregated from all directions.
Marines waiting to debark shouted derisively at the sharks; but it was noticeable that they didn't pull any funny business on the slings, and they didn't let go of the slings until their feet were firmly planted in the bottom of the landing craft. The landing craft scarcely rose and fell. The Caribbean was as smooth as an inland lake. I think, now that I look back, that all of us had a strange feeling that something unusual was going to happen, and that it had nothing to do with the sharks.
I was first aboard a landing craft. I moved to the outboard side of my craft and looked toward the half-moon beach where the Yataritas empties into the Caribbean. The river's mouth was hidden by the sandy beach. To my right the coast of Cuba, rugged, dirty coral cliffs ten to fifty feet high, led away eastward, bulging out gradually a mile south of the white-sandy beach. To my left there were broken cliffs of rotting coral, and slopes leading up gradually from the shore to cactus and spined-brush-covered hills so round they cast no shadows.
Captain Ross Haggerty crawled down into the second LCVP, First Lieutenant Peter Hoose into the third. There were twenty-four men with each of us, some veterans of two wars, some recruits who'd been too young for World War II.
We were going in with Haggerty to my right rear, Hoose to my left rear. We were equipped with the latest in ship-shore-landing-craft-airplane communications. Four jet planes did fancy stuff over us, over the beach, and behind the beach, while we got into our places. I could talk with anybody in any LCVP, aboard the Odyssey or in any one of the jets. Our headsets made us look like men from Mars.