Blood in the Water: The Attica Prison Uprising of 1971 and its Legacy by Heather Ann Thompson:
A bloody outcome was virtually guaranteed by the NYSP’s choice of weaponry. Two six-man teams of troopers would position themselves on the rooftops of A and C Blocks with rifles at the ready to provide cover for the men launching the assault below. The men leading the assault on D Yard would themselves be armed with .270 caliber rifles, which utilized unjacketed bullets, a kind of ammunition that causes such enormous damage to human flesh that it was banned by the Geneva Conventions. Many of the other troopers and COs preparing to go in were also carrying other weapons that would have a particularly brutal effect, such as shotguns filled with deadly buckshot pellets that sprayed out in a wide arc. As all state officials knew, although there were some gas guns in the yard that could fire tear gas, no prisoner in the yard was carrying a firearm.
Although the men in D Yard preparing for bed late Sunday night had no idea that the NYSP had been given the green light to storm the prison the next morning, they were by no means optimistic that a peaceful end to this standoff was imminent. It was clear to them that Oswald had no intention of removing Vincent Mancusi from his position at Attica, nor was Rockefeller budging on offering full amnesty in exchange for their surrender. And yet, it still wasn’t easy to imagine surrendering. Earlier that day, Herb Blyden had gotten up before the men in D Yard and had made the implications of this crystal clear. Even after being transferred to Attica, he reminded everyone, he still faced “seventy-seven counts” for having rebelled at the Tombs the year before. “All of this came about,” he made clear, “after the Mayor and staff promised us, promised us no reprisals on the T.V. screen.” Before he sat down Blyden said sadly to those looking up at him, “Man, I am not trying to scare you,” but no matter what they say and promise here at Attica, “you’re still gonna die.”