Congress had at first failed to override…

Congress had at first failed to override the Freedman's Bureau veto (a second attempt in July will carry the measure).

The Civil Rights Act of 1866, a United States federal law that is mainly intended to protect the civil rights of African-Americans, in the wake of the American Civil War, had been enacted by Congress in 1865 but vetoed by President Andrew Johnson.

In April 1866 Congress again passes the bill.

Although Johnson again vetoes it, a two-thirds majority in each house overcame the veto and the bill becomes law on April 9, guaranteeing equal treatment of Negroes in the South, and declaring all persons born in the U. S. to be citizens and entitled to equality before the law.

This is the first instance of a presidential veto's being overridden.

Johnson’s vetoes unite Moderate and Radical Republicans in outrage and further polarize an already acrimonious situation.