The post-state history of the Mare Island Dockyard, dating from 1854 to 1996, is quite straightforward and well documented. But how the island just north of San Francisco got its name while in the hands of Spain and Mexico is another story – one full of fact and fiction.

Mare Island was first named Isla Plana or Flat Island by Spanish explorers in 1775. Its present name, according to a generally accepted story, derives from an accident in Carquinez Strait involving a mare owned by Lt. of the Mexican Army Mariano Vallejo.

One version of the story has the mare falling off a crude raft and ending up on the island, and another version has the mare running away from the horses that Lt. Vallejo and other soldiers were swimming through the strait. The horse managed to reach Isla Plana, on the north side of the strait, where he was spotted a few days later. After that, Isla Plana was renamed Isla de la Yegua, or Mare Island.

According to a lengthy U.S. Navy report housed in the Mare Island Museum, Vallejo named the island in early 1830 following a mapping expedition north of San Francisco Bay. But that conflicts with another story, mentioned in an 1867 Vallejo Recorder article, that the name originated from the use of the island by early Mexican rancheros for grazing horses.

It is not known when this grazing began, but the island was granted in May 1841 to Victor Castro who said Indians were stealing his horses from the mainland and he needed a safe place for his broodmares. Some stories say Castro came up with the name Mare Island, but it’s on an 1840 Mexican map of the area and Castro, in his petition for the island, indicated that the name already existed.

There is another story about a wild mare seen among a large herd of elk on the island, hence the name Mare Island. Navy Lieutenant Joseph W. Revere said in his 1849 book, A Tour of Duty in California, that he saw the mare leading a herd of elk while on a hunting trip in 1846 on Mare Island. In his 1885 book El Dorado, author Bayard Taylor gives a similar explanation for the island’s name.

Based on a review of numerous articles, reports, and books that mention Mare Island by name, my vote is for the story of the mare drifting across the Carquinez Strait by Lt. Vallejo in 1830.

Dr. Plato Vallejo, the son of Mariano Vallejo, said in a 1914 family memoir that the soldiers swam the horses through the strait near the point where it empties into San Pablo Bay. It would be near what is now Crockett on the south side of the strait to what is now the town of Vallejo on the north. The crossing was also used in 1835 to barge about 600 head of cattle to the north side. From there, the vaqueros drove the cattle to Sonoma, the headquarters of Vallejo who, a year later, became the general commander of Mexico’s northern frontier.

Other documents attribute the name of Mare Island to a Strait of Carquinez crossing a few kilometers upstream, from present-day Martinez to Benicia. These reports include a quarterly California Historical Society article from 1927 on Benicia’s founder, Robert Semple, who ferried travelers through that end of the strait beginning in the mid-1840s. Semple, a boat that can carry up to eight horses, capsized during a squall and a mare belonging to General Vallejo was swept downstream by strong currents towards what was ‘forever’ known as the Sea Island.

Boaters familiar with the Carquinez Strait know that the currents can be strong enough to carry anything floating from Benicia to Mare Island in an hour or two. But the problem with the story of the capsized Semple ferry is that it happened about 15 years after the renaming of the island from Plana to Yegua described in the memoirs of Plato Vallejo.

Semple’s story also says that the horse that ended up on Mare Island was “an old white mare”. There are many articles and newspaper articles that mention the white horse – and many more, including a monthly account by Scribner from April 1872, that indicate it was grey. Plato Vallejo’s description does not mention any color or age for the horse – only that it was “a beautiful mare”.

The various stories told over the years about the naming of the Mare Island tale have all sorts of embellishments that go far beyond Plato Vallejo’s version. An 1892 story in the San Francisco Call, for example, has General Vallejo almost in tears after seeing his “precious” mare sink in the strait, then several weeks later to “his surprise and delight” to find the horse. on Mare Island. “The general called her by name and she ran whinnying to his side,” the article said. Oh good?

Many stories also describe the fall of the mare from a raft made of barrels covered with logs which pitched badly in choppy water. It is likely that such rafts were used to transport cattle but, again, these versions conflict with Plato Vallejo’s account of his father and other soldiers swimming the horses across the strait.

Finally, General Vallejo is credited in many stories for naming the island of Mare. But Plato Vallejo says the name was chosen by Commandant Mariano Vallejo when soldiers leading the 1830 mapping expedition returned to Monterey and described how the mare was lost and then found to safety.

Ultimately, there is no certainty as to the naming of Mare Island. It seems reasonable to go with Plato Vallejo’s version, since he based it on the stories his father told him. But Plato was also known as a storyteller who, in the words of one historian, had “a penchant for testing the limits of credulity.” This is your call on what to believe, readers.

– Vallejo and other Solano County communities are treasures of California history. The Solano Chronicles, which airs every other Sunday, highlights various aspects of this story. My source references are available upon request. If you have local stories or photos to share, email me at [email protected] You may also send any materials c/o The Times-Herald, 420 Virginia St.; or the Vallejo Naval and Historical Museum, 734 Marin St., Vallejo 94590.