Visit Flanders Field from Brussel, Belgium

Using the Belgian rail site
www.belgianrail.be And picking Bruxelles and Ypres, it looks like it takes 1 hour and 45 minutes to take the train. It looks like there are trains every hour from about 5:32 in the morning onward. Some seem direct, others seem to show 1 change of trains. I don't know what tour you wish to take. I took one from Bruges that left at about 9:00 am. www.quasimodo.be - tour in English. It might also work by taking the train from Brussels to Bruges (which takes an hour) and get a tour from Bruges. Then you can ask them to leave you in Ypres (Ipers in Dutch) and catch the train back from there. A couple did the tour starting in Brugges with us, did the whole tour and then a cab was arranged from the last stop (where the poem "In Flanders Fields" was written)for them back to Ypres. They wanted to experience the nightly tribute, "Last Port" to the missing soldiers which occurs in Ypres at 8 pm. return train times are similar - leaving Ypres at 19:41, 20:39 etc. Takes about 1 hour and 50 minutes to get back. I think you can do it with some advance planning and as long as you are up for a long day.

It might be more convenient to rent a car for one day. Easy enough to reach Ieper (I use the Dutch spelling because that's what all the rail and road signs will use) by rail, but all the memorials are spread out over a fairly large area. The city center of Ieper itself is pretty compact, but the location of most of the war-relates sites are not. Of course, this won't matter if you take an organized bus tour.

Just a correction - make that "Last Post" in Ypres. Important to correct that I think.