The Prehistoric Age of Sandwich MEV Before the Bundle: When Gas Auctions Ruled the Chain
How open mempools, gas wars, and one Bancor swap gave birth to Ethereum’s earliest predators.
In the hidden lanes of Ethereum’s blockspace, a new kind of creature has evolved—stealthy, adaptive, and precision-engineered for profit. These aren’t just bots. They are financial predators with a genetic lineage shaped by protocol quirks, mempool mechanics, and incentive asymmetries.
This multiple-part series dives deep into the evolutionary history of sandwich MEV—one of the most misunderstood yet impactful phenomena in the crypto ecosystem. We’ll track how this strategy morphed from single-line scripts to industrial-scale operations, revealing what each transformation tells us about the economics, architecture, and future of Ethereum itself.
If you think sandwiching is just front-running whales, think again.
Welcome to the Mempool Jungle
Picture Ethereum’s mempool as an endless Amazon River at night: crystal‑clear water, every fish illuminated by a flashlight…while piranhas circle with sniper goggles. Transparency gives us radical auditability—but it also lets predators stalk their prey with millisecond precision. Sandwich attacks are those piranhas. And, like real species, they’ve been evolving fast.
Here is how the story of Sandwich begins.
Gas‑Guzzling Guessers – How Ethereum’s First Predators Learned to Hunt in the Pre‑industrial, “spear‑and‑stone” hunting Era
A Bite Called “Sandwich”
Imagine you’re at an open‑air market, ready to swap apples for oranges. Just as you hand over your basket, someone darts in front of you, buys the last cheap oranges, watches you pay the marked‑up price, then sells those same oranges back at a tidy profit. On Ethereum that maneuver is called a sandwich attack: a bot places one trade just before yours and one just after, trapping you in the middle and pocketing the difference.
Why could it happen at all? Because in Ethereum’s early days the checkout line was sorted by gas price—pay more and you cut to the front.
Enter the Priority Gas Auction
Back in 2014, during Ethereum’s crowdsale, a curious Redditor already asked, “What stops miners from putting their own transactions ahead of mine?” That innocent question foreshadowed the gas‑price bidding wars to come.
With no other sorting rule, trading bots soon turned the mempool into what researchers later dubbed the Priority Gas Auction (PGA). Think of a street auction where every bid must exceed the last by a few pennies—but here each bid is a replacement version of the same transaction, broadcast again and again with a higher fee.
A famous chart from the paper Flash Boys 2.0 captures the frenzy: two bots spotted the same arbitrage, raised their gas bids 2,900 times in fifteen seconds, and drove the price of inclusion from 25 gwei to 8,800 gwei. One bot won; the other burned money on thin air.
2018 — Theory Meets Reality on Bancor
The earliest confirmed sandwich was excavated by 1inch in February 2018.
A bot paid 37.9 gwei to slip a small buy order into a Bancor pool.
An unsuspecting trader followed at 33 gwei, buying tokens at a suddenly worse rate.
The bot immediately sold at 32.9 gwei, restoring prices and netting almost a tenth of an ETH—small in dollars, but priceless as proof of concept.
From that moment, the sandwich moved from whiteboard speculation to everyday hazard.
The Hidden Cost of the Gas War
Within just a couple of years, the mempool looked less like an orderly queue and more like rush‑hour traffic—horns blaring, everyone inching forward by overpaying. The PGA created two systemic aches:
Winner‑takes‑all economics. Only the top bid earned profit; every loser still paid real gas, like gamblers covering the house edge.
Fee inflation for bystanders. As bots escalated, average transaction costs rose for everyone else. Even slippage settings—meant to protect traders—acted as neon tags telling bots exactly how much value they could safely steal.
All told, the on‑chain incentive scheme no longer felt fair: honest swappers subsidised high‑frequency gas wars, and the whole network groaned for a remedy that could level the playing field.
Wrapping Up the Era
Open mempool, frantic gas spam, and a knife‑fight where predators sometimes slashed one another—this was Ethereum’s spear‑and‑stone age of MEV. The remedy would come in the next chapter: sealed‑bid bundles that whisk trades out of the public queue and into quieter, private tunnels. But as we’ll soon see, a safer road for users also became a super‑highway for a new generation of predators excelling at atomic ambushes, tunnel warfare, and financial camouflage.
Coming Up Next: Gas Wars to Bundle Tunnels
In the next chapter, we follow the rise of Flashbots, the sealing of Ethereum’s public mempool, and how private coordination gave predators their most powerful tool yet: invisibility.
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