The crux of the problem was that in passing the measure the 42nd Congress made it retroactive to the start of their term in office.  Adding to the furor was its inopportune timing.  Rumors and revelations of government scandals were pervasive, particularly concerning the Credit Mobilier affair, so the press and public tended to respond with cries of "corruption!"  Others charged the Republican-controlled Congress with hypocrisy since the Party's candidates had run on a platform of government economy the previous fall.

The House bandied the proposal back and forth, approving it, rescinding it, and approving it again.  Finally, the measure passed both houses in early March 1873 and the president signed it into law.  A volcano of vitriol spewed forth upon its supporters.  Voters wrote nasty letters, editors slammed the Salary Grab, state legislatures passed resolutions of censure, and local conventions called for resignations.  Even someone like Congressman James Garfield, who opposed the bill on the House floor and in the House-Senate conference committee, was subjected to abuse for signing the committee's report.  (He was also implicated in the Credit Mobilier scandal.)

For Harper's Weekly and other publications the focal point of condemnation was Congressman Butler, the law's sponsor and, to the horror of the party establishment, a candidate for the Republican gubernatorial nomination in Massachusetts.  Instead of retreating on the issue, Butler snapped back at critics, ardently defended the pay increase, contemptuously sent carping constituents 3-cent stamps as their share of the loot (notice his medallion in the cartoon) , and brazenly used the money (which his more timid colleagues had returned) for an ocean cruise.

In the fall, Butler lost the governor's race and the Republicans suffered substantial losses in the state elections of Minnesota, New York, Ohio, and Wisconsin.  Many issues were involved in the political turnaround, including the Panic of '73 that soon slid into a full-fledge economic depression.  The Salary Grab scandal, however, was a key topic of debate in all the campaigns and had clearly been one factor in the election results.  In December, congressmen fell over each other to introduce bills to repeal the salary increase, and both houses quickly passed such a measure.

The cartoon also refers to the Modoc Indians.  They had been removed from their homeland in southern Oregon and northern California and placed on a reservation in Oregon where their traditional enemies, the Klamath Indians, already resided.  Harassed by the Klamath, a group of nearly 400 Modoc left the reservation in April 1869 and returned to their homeland.  In late November 1872, at the insistence of white settlers, the U.S. Army attempted to force the Modocs back to the Klamath reservation.  Fighting over the next several months was called the Modoc War, and featured a Modoc nicknamed Captain Jack.  He and his Modoc brethren finally surrendered on June 1, 1873, shortly after this postdated cartoon was published.  

Although a group of the Indians who had killed 14 settlers were pardoned, Captain Jack and three other Modoc leaders were executed on October 3, 1873 for their role in an attack on federal peace commissioners in which General E. R. S. Canby and another commissioner were killed.  The remaining Modoc were placed on a reservation in the Indian Territory (Oklahoma).  An earlier request by the Modoc for their own reservation would have cost the federal government $20,000; instead, they expended over $1,000,000 to subdue the Modoc in a war that took numerous lives on both sides.