String date = "5th Apr 1920";
LocalDate.parse(date, DateTimeFormatter.ofPattern("d MMM yyyy", Locale.ENGLISH));
this prases DateTimeParseException.
If pattern is "d'th' MMM yyyy", it works. But it is unsuitable when string is "1st Apr 1920".
Just specify more options:
LocalDate.parse(date, DateTimeFormatter
.ofPattern("d['th']['st']['nd']['rd'] MMM yyyy", Locale.ENGLISH))