He co-authored major historical works on the Dutch States Army and the Campaign of 1815, which climaxed with the Battle of Waterloo.

In the social circumstances of the Dutch army of the time the scandal also reflected on the father and he was no longer considered worthy of advancement.

As a student at the Staff College he had been seconded in 1870 to Lieutenant General Willem Jan Knoop, the doyen of Dutch military historians at the time.

Knoop had made the suggestion in 1858 to the Royal Netherlands Academy of Arts and Sciences to collect the Dutch military archives and make them available for publication.

Though this proposal was not followed at the time, the Minister gave him a commission to start collecting sources on Dutch military history.

In the latter function he negotiated in 1900 with the head of the House of Nassau, Adolphe, Grand Duke of Luxembourg, on behalf of Queen Emma of the Netherlands about the right of the descendants of her daughter, Queen Wilhelmina, who was about to marry Duke Henry of Mecklenburg-Schwerin, to keep using the Nassau name.

The work may be seen as an attempt to redress the often disparaging account given in especially Anglophone historical works, like the ones by William Siborne and his son Henry Taylor Siborne, and the British historians that based themselves on their sources, of the conduct of the Dutch and Belgian troops and their commanding officers at those battles.

The first volume of this work was published in 1911 and De Bas used his position as head of the military-history section to have himself named as co-author of this book, though it was virtually entirely written by Ten Raa.

He remained at the military-history section till bad health forced him to resign in 1927, almost 87 years old at the time.