The closest thing to an official history of the background of today's feast day seems to be very cautious about being as "correct" as possible with the circumstances of the martyrdom. These things should really be written by objective historians, preferably with no denominational political attachments to constrain their commentary.
I'll refer you here and simply note that, while unmentioned in the entirety of the article, it was the Japanese who executed the members of the Anglican mission. It's okay if we say that because, after all, it's history. I mean, real history as opposed to political history. Real history is the one with the facts; facts that carry no political weight but simply state what was.
Also, the martyrs were not "arrested". They were captured. This wasn't a police raid on some bootleggers or in a tatty burlesque house; it was a war. The mission leaders, eight clergy and two laity, were executed summary to their capture on this day in 1942.
An interesting note: A statue of Lucian Tapiedi, the only indigenous Papuan among the martyrs, is installed, along with other Christian martyrs, in the niches over the west door of Westminster Abbey. He's the one on the left in the photo above. No, that's not mentioned in the official piece, either.
[The one on the right is Wang Zhiming, martyred in his native China during the "cultural revolution" in 1973.]