It was the south who killef
Jefferson who? what letter? This question isn't specific enough.
The Emancipation Proclamation issued by President Lincoln made enslaved African-Americans free once they crossed the border into Northern territory. This eventually freed all former slaves, as the Confederate Army lost the Civil War. This presidential order was issued on the first of January in the year of 1863.
Answer:
a system of consolidating many firms in the same business