For full dates, write10 June 1921 orJune 10, 1921, consistently throughout an article (10 June orJune 10 where the year is omitted). Generally, use themonth first format for (1) US-related articles, and (2) articles not related to a native English-speaking country that already use themonth first format.
Avoid changing a consistently used date format in an article just for reasons of personal preference.
