Webster's Revised Unabridged Dictionary · 1913

Thereupon

Thereupon , adverb

1.
Upon that or this; thereon.
They shall feed thereupon. — Zeph. ii. 7
2.
On account, or in consequence, of that; therefore.
[He] hopes to find you forward,... And thereupon he sends you this good news. — Shakespeare
3.
Immediately; at once; without delay.