Conversation so far:
when did they start building the london underground
The history of the London Underground began in the 19th century with the construction of the Metropolitan Railway which opened in 1863.
did any disasters happen in 1863
The blizzard and flood of 1863 was a series of consecutive natural disasters in Central Otago in New Zealand's South Island.

Question: how many people died in the series of disasters
Self-contained rewrite: how many people died in The blizzard and flood of 1863