What does it mean by "bondsman's two hundred and fifty years of..." in Lincoln's 2nd inaugural adress?

In English, the word "man" means both an adult male human being and all human beings regardless of age or sex. The distinction being purely contextual.

The word bondman meaning a man bound to serve without wages, i.e. a slave, came into English in the 12th Century. It appears in the King James Version of the Bible (in the UK, the Authorized Version) in six places as synonym for slave. The term is not contextually gendered.

Lincoln used it in that sense in his Second Inaugural Address. The address has been transcribed several times. You may inspect images of the autograph on the Library of Congress web site. To me, it appears that Lincoln wrote bond_man, and that the underscore was most likely an attempt to correct an accidental break in the cursive lettering.

The Collected Works of Abraham Lincoln, available online, transcribes the word "bond-man" with a dash rather than an underscore. While the Yale Avalon Project transcribes it as "bondsman", the usage above.

I think that Lincoln's intent was to use the word from KJV, "bondman", and that Avalon is wrong, and Collected works should have noted the variation.

The word bondsman is an English word found in standard dictionaries. It means a surety or a man who has given a deposit of valuable collateral to guarantee the performance of an obligation, most often the obligation of a man accused of a crime to appear in court. It originated in the 18th Century. It is clearly not the word Lincoln intended to use in discussing the American Civil War and its connection to the institution of slavery of African descended human beings.

Lincoln would not have used the word "bondsperson". It is a neologism invented within the last 30 years.

In the 1970s, radical feminists declared that the use of the word man and men to refer to all human beings was an insult to women, and that it should henceforth cease. Many academics and many lawyers obeyed this diktat. The word person which was used in the law to refer to both individual humans and to legal fictions, such as corporations, which have legal rights analogous to those of individual humans, was dragooned into use as a substitute for the word man particularly in compounds, e.g. chairperson for chairman.

Bondsperson, has in some statutes replaced bondsman. Both refer to sureties, not to slaves.

A bondsman is the lienholder or "one who has title." A Lord or Admiral or some such thing is your proto-typical "bondsman" and straight up...he ain't toiling much. In short all that "time"(250 years) of "so called work"(toil from the bondsman) will mean nothing gets done or accomplished. Nothing of "lasting value" will be created. Lincoln was a Railroad Lawyer first and foremost. He knew what "paying the bondsman" in fact meant (the track got laid but no locmotive and rolling stock followed) so this is, was and remains a very obvious and practical thing to say to the American People circa 1865.

"all the wealth piled by the bondsman's two hundred and fifty years of unrequited toil" refers to the material gains extracted from the labors of the African slaves brought to North America continuously from 1619 to 1864. A "bondsman" in the common parlance of the day was a slave, and Lincoln was well aware that slaves had been instrumental in the building of America from the very start. He also knew that money and loot might not be enough to atone for our sins, hence the further warning that the war might need to continue until "every drop of blood drawn with the lash shall be paid by another drawn with the sword". Explaining it thusly leaves nobody off the hook - slavery is the sin of us all, not simply the South. So be it.