Surmiser

It is surmised that he traveled in Italy and Germany and around, and qualified himself to put their scenic and social aspects upon paper; that he perfected himself in French, Italian, and Spanish on the road; that he went in Leicester's expedition to the Low Countries, as soldier or sutler or something, for several months or years--or whatever length of time a surmiser needs in his business--and thus became familiar with soldiership and soldier-ways and soldier-talk and generalship and general-ways and general-talk, and seamanship and sailor-ways and sailor-talk.

And according to the surmisers, that is what he did.