what does "were" mean?
The assassination did not signal a sneak attack, so the price of folly was unpaid. Instead, the lesson was written on the slate of time in cosmic letters and left to be learned. Llewellyn Thompson's apprehension is another matter. Appraising it must be left to those who evaluate Lyndon Johnson's foreign policy, and an account of the transitional period during which he came to power is clearly not the place for that. Perhaps Thompson's misgivings were completely without foundation. McCone's were, as he readily conceded the following spring. By then— indeed, almost from the moment he reached the capital—Johnson had taken hold with remarkable forcefulness.】
what does "McCone's were"mean?