If a country ran into a liquidity problem, the US would provide the needed liquidity in USDs.

FORBES: Our Fiat Dollar Has Cost the United States $80 Trillion

However, after 1958, when the economies of other countries began to recover and the trade surpluses began to decline, they quickly accumulated USDs.

FORBES: Our Fiat Dollar Has Cost the United States $80 Trillion

This meant that countries holding USDs as reserve currency were under increasing pressure to convert their USDs into gold to protect their own positions.

FORBES: Our Fiat Dollar Has Cost the United States $80 Trillion

Fourth, the fantastic costs associated with the Vietnam War created huge inflationary pressures which drove down the value of USDs as compared with gold (even at the fixed rate of exchange).

FORBES: Our Fiat Dollar Has Cost the United States $80 Trillion