Your question cannot be answered because you didn't tell us what "they" refers to.
one day (june 6 1944)
The Battle of Bunker Hill only lasted a day. It was fought on June 17, 1775.
240 days
two days
3 days
There are 6 days in the last six days.
The Last Days - novel - has 286 pages.
3 days
3 Days
20 days...=)
2 days
five days
On average, 7 days.
1-2 days
150 days.
Couple days
12 days the fire lasted