"The Recruiting Serjeant Taken in, or all Fair Above Board"(1791).
Depicts a man with a wooden leg being recruited.

THERE WERE TWO REASONS WHY MEN TRIED TO FAIL THE ARMY MEDICAL EXAM.  First, the recruit had been tricked into enlisting; or, second, they were hustlers who enlisted repeatedly to defraud the recruiters out of bounty money, food, drink, and lodging.

In the Napoleonic Wars, the British recruiting system was broken.  A major problem was the responsibility put on inspecting army surgeons (medical officers).  If the surgeon allowed a recruit to pass that was in fact unfit to serve, he was held financially accountable for all the expenses of that failed recruit.  In short, army surgeons were motivated not to pass those they inspected.

How the process worked was, the recruit was brought by the recruiting party to the medical officer.  Upon arriving at the surgeon's residence, one recruit described what happened next:  “I was called in first and stripped naked and examined carefully as to soundness of my internal systems, the limbs, and the eye sight.  I was ordered to walk fast and slow and put my body in different positions of difficulty.” 

In accordance with regulations, the surgeon had to "ascertain that he has no rupture, that he has the perfect use of his eyes and ears, and free motion of every joint and limb; that he has no tumours, nor diseased enlargement of the bones and joints; no sore leg, nor mark of an old sore; that his appearance is healthy, that he is neither consumptive nor subject to fits."  

At this stage of the recruiting process, the hustler played the role of being unworthy for the military and either revealed a hidden affection or faked one:

  "Some excite ulcers; others affect stammering, deformity, pain in various parts of the body, deafness, blindness, epilepsy, contractions of the finger, lameness, etc."  

Wrote one surgeon: "We sometimes meet with individuals who refuse to move an arm or leg, and assert that they have lost the power of motion in the limb."   The lengths some men took to get rejected were simply astounding.  Teeth were either pulled out or filed down.  Others made small incisions inside their mouths so they could fake spitting up blood.   A crafty few drank bull's blood prior to seeing the surgeon and then induced vomiting.  Some even injected blood into their bladder so they could urinate blood.   

One of the strangest was the faking of haemorrhoids.   This was affected by the recruit by taking the bladder of a rat or small fish, and inserting it partially in his rectum!  An unwise few drank a dangerous mixture of vinegar and burnt cork or shoe blackening (which contained high concentrations of poisonous sulphuric acid) in order to trigger diarrhea or dysentery. 

Scurvy was simulated by covering the teeth with wax and then applying a corrosive substance to their gums.  Even jaundice was replicated by painting/dying the perpetrator's skin yellow and employing smoke in the eyes to mimic that disease's physical traits. Still others pretended to have mental illness, ear ulcers, and incontinence.  At least one tried to fake a growth inside his nose by inserting a rooster's testicle inside, holding it place with a small sponge.  Some even resorted to self-mutilation and maiming to get rejected. One even tried to fake death!

In the end, the combination of medical officers with a disincentive to pass recruits and the creativity of men wishing to be rejected, severely damaged the British Army's to secure able-bodied replacements in a time of war.  The only thing that saved the war effort was the introduction of volunteer transfers from the militia to regular forces.