The only thing about early life widely known was that John was born into the Grady family on Christmas Day in 1872 somewhere in New Brunswick. By the summer of 1890 he was in Massachusetts signing up for service.
By May of 1901 he had risen through several ranks and was promoted to a Warrant and with the trade of Gunner. Three years and several ships later he would be promoted to Ensign, would soon skip the next rank and get an accelerated promotion to naval Lieutenant.

This vessel was under the command of the Naval Captain, (and much later), Admiral Anderson. This is the same officer that during the Spanish American War commanded two of the USS Marblehead's launches that were involved in the cable cutting incident where several Canadians earned Medals of honor.
Mexico was in troubled times in those days. Several governments had been ousted in short order and at the time the country was being ruled by a dictator who came to power via a coup. US President Wilson did not like this and was of course concerned about the Americans in Mexico and the US interest within the country. He kept gun boats not far off shore for awhile and when learning of an expected arrival of a cache of arms, he ordered the navy to land her marines and artillery to ensure the cache was not landed. Complicating matters the Mexicans had most recently arrested several sailors and also boarded a US boat and seized others who were on a mission of resupply. Within days matters started to bubble over and the President ultimately got permission to land about 7,000 sailors and marines and soldiers to take control of Vera Cruz.
Lt John Grady was put in charge of a navy/marine artillery unit and on day two of a three day insurrection Grady had to set up and man a heavy gun position in the streets of Vera Cruz. He came under very heavy fire from snipers positions inside buildings, from rooftops and the streets. He shelled the city from numerous locations and did so in such a manner despite the shooting all around him, that he would later be recommended for, and awarded manned a Medal of Honor.
There have been over 30 times when sailors have landed and acted as marines or soldiers in battle, but this was the first time ever that a Naval officer would earn a MOH with the naval artillery. While the fighting only took a few days and most would soon be back on their vessels and most off to other duties, 55 men would earn MOH's in this campaign.
John Grady continued his service throughout WW1 and was promoted to Lt Commander and then acting Commander. Shortly after the war came to an end he was confirmed in rank as a Commander. During the later part of the war Grady was given command of three different war ships. Grady would also become one of only 8 men at the time that had been awarded a MOH and later also be awarded the Navy Cross. His being awarded ..." For distinguished service in the line of his profession as commanding Officer of the USS Wilhelmina, engaged in the important, exacting and hazardous duty of transporting and escorting troops and supplies to European ports through waters infested with enemy submarines and mines."
In December of 1921 Grady was appointed to the General Court Martial Board at new York and he took his retirement the following year. He would be called out from the retirement list briefly in WW11, with the confirmed rank of Commander, promoted to Naval Captain and within short order again took retirement,

His wife lies at his side.
At death he had two sons, one following in his footprints and at that time was a naval Lt. Commander himself.
Yesterday was the anniversary of the 99th year of the same date in 1914 when Grady's heroism resulted in his receiving the Medal of Honor.
Bart