In the spring and summer of 1943 in Amsterdam, Johan van Hulst was at the center of a daring scheme to save Jewish children from being sent to a concentration camp.

The children — from infants to 12-year-olds — had been taken from their parents at a deportation center and brought by nursery workers to a nursery next to the teachers’ college where Mr. van Hulst was the principal.

The rescue plan was simple but risky: the children were surreptitiously handed over a hedge between the nursery and the college and hidden in a classroom until they could be smuggled to the countryside by Dutch Resistance groups.

Mr. van Hulst is credited with helping to rescue as many as 600 children, yet he was haunted by what he could not do. With up to 100 children still in the nursery as it was about to be shut down that September, Mr. van Hulst was asked how many more he could smuggle out.