Realizing soon that this was not sufficient to restore calm and confidence to the markets, they had to follow up the conventional measures with a slew of unconventional measures variously described as quantitative and credit easing.
The first wave of unconventional measures was aimed at providing liquidity to the system either by way of collateralized loans through the repo window or outright purchase of bonds. Liquidity management is of course standard monetary policy procedure. What made this unconventional were mainly two things. The first was the quantum of operations.